diff --git a/bsp/CME_M7/drivers/emac.c b/bsp/CME_M7/drivers/emac.c
index 2582eab805..5665a95548 100644
--- a/bsp/CME_M7/drivers/emac.c
+++ b/bsp/CME_M7/drivers/emac.c
@@ -228,13 +228,13 @@ static rt_err_t rt_cme_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_cme_eth_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_cme_eth_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_cme_eth_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_cme_eth_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/Infineon/libraries/HAL_Drivers/drv_i2c.c b/bsp/Infineon/libraries/HAL_Drivers/drv_i2c.c
index 86c52f8906..5a91a99cf4 100644
--- a/bsp/Infineon/libraries/HAL_Drivers/drv_i2c.c
+++ b/bsp/Infineon/libraries/HAL_Drivers/drv_i2c.c
@@ -90,7 +90,7 @@ static int ifx_i2c_write(struct ifx_i2c *hi2c, uint16_t slave_address, uint8_t *
     return 0;
 }
 
-static rt_size_t _i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t _i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
     rt_uint32_t i;
diff --git a/bsp/Infineon/psoc6-pioneerkit_modus/drivers/uart.c b/bsp/Infineon/psoc6-pioneerkit_modus/drivers/uart.c
index 16be3266f1..c750f7c9dc 100644
--- a/bsp/Infineon/psoc6-pioneerkit_modus/drivers/uart.c
+++ b/bsp/Infineon/psoc6-pioneerkit_modus/drivers/uart.c
@@ -94,7 +94,7 @@ static rt_err_t rt_uart_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_uart_read (rt_device_t dev, rt_off_t pos, void* buffer,
+static rt_ssize_t rt_uart_read (rt_device_t dev, rt_off_t pos, void* buffer,
                                  rt_size_t size)
 {
     rt_uint8_t* ptr;
@@ -154,7 +154,7 @@ static rt_size_t rt_uart_read (rt_device_t dev, rt_off_t pos, void* buffer,
     return (rt_uint32_t)ptr - (rt_uint32_t)buffer;
 }
 
-static rt_size_t rt_uart_write (rt_device_t dev, rt_off_t pos,
+static rt_ssize_t rt_uart_write (rt_device_t dev, rt_off_t pos,
                                 const void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
diff --git a/bsp/acm32/acm32f0x0-nucleo/drivers/drv_i2c.c b/bsp/acm32/acm32f0x0-nucleo/drivers/drv_i2c.c
index dedf02710b..3ee4cc928b 100644
--- a/bsp/acm32/acm32f0x0-nucleo/drivers/drv_i2c.c
+++ b/bsp/acm32/acm32f0x0-nucleo/drivers/drv_i2c.c
@@ -84,7 +84,7 @@ static int acm32_i2c_write(struct acm32_i2c *hi2c, uint16_t slave_address, uint8
     return 0;
 }
 
-static rt_size_t _i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t _i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
     rt_uint32_t i;
diff --git a/bsp/acm32/acm32f0x0-nucleo/drivers/drv_uart.c b/bsp/acm32/acm32f0x0-nucleo/drivers/drv_uart.c
index 64951270ff..ca1c7daf8d 100644
--- a/bsp/acm32/acm32f0x0-nucleo/drivers/drv_uart.c
+++ b/bsp/acm32/acm32f0x0-nucleo/drivers/drv_uart.c
@@ -275,7 +275,7 @@ static void dma_rx_done_isr(struct rt_serial_device *serial)
     HAL_UART_Receive_DMA(&(uart->handle), &rx_fifo->buffer[rx_fifo->put_index], serial->config.bufsz);
 }
 
-static rt_size_t _uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t _uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     struct acm32_uart *uart;
     RT_ASSERT(serial != RT_NULL);
diff --git a/bsp/acm32/acm32f4xx-nucleo/drivers/drv_uart.c b/bsp/acm32/acm32f4xx-nucleo/drivers/drv_uart.c
index c84c6bfeff..a8a599d3c5 100644
--- a/bsp/acm32/acm32f4xx-nucleo/drivers/drv_uart.c
+++ b/bsp/acm32/acm32f4xx-nucleo/drivers/drv_uart.c
@@ -274,7 +274,7 @@ static void dma_rx_done_isr(struct rt_serial_device *serial)
     HAL_UART_Receive_DMA(&(uart->handle), &rx_fifo->buffer[rx_fifo->put_index], serial->config.bufsz);
 }
 
-static rt_size_t _uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t _uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     struct acm32_uart *uart;
     RT_ASSERT(serial != RT_NULL);
diff --git a/bsp/airm2m/air105/libraries/rt_drivers/drv_i2c.c b/bsp/airm2m/air105/libraries/rt_drivers/drv_i2c.c
index ca8feab600..e4ade74c8f 100644
--- a/bsp/airm2m/air105/libraries/rt_drivers/drv_i2c.c
+++ b/bsp/airm2m/air105/libraries/rt_drivers/drv_i2c.c
@@ -14,10 +14,10 @@
 #ifdef BSP_USING_I2C
 
 static struct rt_i2c_bus_device prv_air105_i2c;
-static rt_size_t air105_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t air105_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num);
-static rt_size_t air105_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t air105_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num);
 static rt_err_t air105_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -32,7 +32,7 @@ static const struct rt_i2c_bus_device_ops air105_i2c_ops =
 };
 
 
-static rt_size_t air105_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t air105_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num)
 {
@@ -81,7 +81,7 @@ static rt_size_t air105_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
     }
     return i;
 }
-static rt_size_t air105_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t air105_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num)
 {
diff --git a/bsp/airm2m/air105/libraries/rt_drivers/drv_usart_v2.c b/bsp/airm2m/air105/libraries/rt_drivers/drv_usart_v2.c
index d83fcb3a92..cfe5419eb8 100644
--- a/bsp/airm2m/air105/libraries/rt_drivers/drv_usart_v2.c
+++ b/bsp/airm2m/air105/libraries/rt_drivers/drv_usart_v2.c
@@ -262,7 +262,7 @@ static int air105_getc(struct rt_serial_device *serial)
     }
 }
 
-static rt_size_t air105_transmit(struct rt_serial_device     *serial,
+static rt_ssize_t air105_transmit(struct rt_serial_device     *serial,
                                        rt_uint8_t           *buf,
                                        rt_size_t             size,
                                        rt_uint32_t           tx_flag)
diff --git a/bsp/airm2m/air32f103/libraries/rt_drivers/drv_usart.c b/bsp/airm2m/air32f103/libraries/rt_drivers/drv_usart.c
index 3a9180cde7..b1e30f9b99 100644
--- a/bsp/airm2m/air32f103/libraries/rt_drivers/drv_usart.c
+++ b/bsp/airm2m/air32f103/libraries/rt_drivers/drv_usart.c
@@ -275,7 +275,7 @@ static int air32_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t air32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t air32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     return 0;
 }
diff --git a/bsp/allwinner/d1s/ports/partition/partition.c b/bsp/allwinner/d1s/ports/partition/partition.c
index 37e3dbcb7b..9b9ceb2c37 100644
--- a/bsp/allwinner/d1s/ports/partition/partition.c
+++ b/bsp/allwinner/d1s/ports/partition/partition.c
@@ -78,7 +78,7 @@ static rt_err_t partition_control(rt_device_t dev, rt_uint8_t cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t partition_read(rt_device_t dev,
+static rt_ssize_t partition_read(rt_device_t dev,
                                    rt_off_t pos,
                                    void* buffer,
                                    rt_size_t size)
@@ -93,7 +93,7 @@ static rt_size_t partition_read(rt_device_t dev,
     return rt_device_read(part->block_device, pos + part->partition->offset/part->sector_size, buffer, size);
 }
 
-static rt_size_t partition_write(rt_device_t dev,
+static rt_ssize_t partition_write(rt_device_t dev,
                                     rt_off_t pos,
                                     const void* buffer,
                                     rt_size_t size)
diff --git a/bsp/allwinner/libraries/drivers/drv_i2c.c b/bsp/allwinner/libraries/drivers/drv_i2c.c
index 91897be4e5..ad4515d8fe 100644
--- a/bsp/allwinner/libraries/drivers/drv_i2c.c
+++ b/bsp/allwinner/libraries/drivers/drv_i2c.c
@@ -24,7 +24,7 @@ struct hal_i2c_bus
 };
 
 //connect am drv to rt drv.
-static rt_size_t _i2c_master_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg *msgs, rt_uint32_t num)
+static rt_ssize_t _i2c_master_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg *msgs, rt_uint32_t num)
 {
     struct hal_i2c_bus *_i2c_bus = (struct hal_i2c_bus *)bus;
     struct rt_i2c_msg *msg;
diff --git a/bsp/allwinner/libraries/drivers/drv_uart.c b/bsp/allwinner/libraries/drivers/drv_uart.c
index 3683072086..18956e5e80 100644
--- a/bsp/allwinner/libraries/drivers/drv_uart.c
+++ b/bsp/allwinner/libraries/drivers/drv_uart.c
@@ -388,7 +388,7 @@ static rt_err_t _uart_configure(struct rt_serial_device *serial, struct serial_c
 static rt_err_t _uart_control(struct rt_serial_device *serial, int cmd, void *arg);
 static int _uart_putc(struct rt_serial_device *serial, char c);
 static int _uart_getc(struct rt_serial_device *serial);
-static rt_size_t _uart_transmit(struct rt_serial_device *serial,
+static rt_ssize_t _uart_transmit(struct rt_serial_device *serial,
                                 rt_uint8_t *buf, rt_size_t size, rt_uint32_t tx_flag);
 
 const struct rt_uart_ops _uart_ops =
@@ -720,7 +720,7 @@ static int _uart_getc(struct rt_serial_device *serial)
     return data;
 }
 
-static rt_size_t _uart_transmit(struct rt_serial_device *serial,
+static rt_ssize_t _uart_transmit(struct rt_serial_device *serial,
                                 rt_uint8_t *buf, rt_size_t size, rt_uint32_t tx_flag)
 {
     struct sunxi_uart *uart;
diff --git a/bsp/allwinner/libraries/drivers/sdmmc/drv_sdmmc.c b/bsp/allwinner/libraries/drivers/sdmmc/drv_sdmmc.c
index 368fcc5369..4b64354f83 100644
--- a/bsp/allwinner/libraries/drivers/sdmmc/drv_sdmmc.c
+++ b/bsp/allwinner/libraries/drivers/sdmmc/drv_sdmmc.c
@@ -232,7 +232,7 @@ rt_err_t sdmmc_deinit(rt_device_t dev)
     return 0;
 }
 
-static rt_size_t sdmmc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t sdmmc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     ssize_t ret, rsz, trsz, msz = 0;
     struct rt_device_blk_geometry *geometry;
@@ -309,7 +309,7 @@ static rt_err_t sdmmc_close(rt_device_t dev)
     return 0;
 }
 
-static rt_size_t sdmmc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t sdmmc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     int err = -1;
     ssize_t ret, wsz, twsz, msz = 0;
diff --git a/bsp/allwinner/libraries/drivers/touch/drv_touch.c b/bsp/allwinner/libraries/drivers/touch/drv_touch.c
index 9cf0260bfe..8361fb1742 100644
--- a/bsp/allwinner/libraries/drivers/touch/drv_touch.c
+++ b/bsp/allwinner/libraries/drivers/touch/drv_touch.c
@@ -152,7 +152,7 @@ int rt_touch_write(rt_uint16_t addr, void *data_buf, size_t data_len)
         return -1;
 }
 
-static rt_size_t touch_readpoint(struct rt_touch_device *touch, void *buf, rt_size_t touch_num)
+static rt_ssize_t touch_readpoint(struct rt_touch_device *touch, void *buf, rt_size_t touch_num)
 {
     rt_device_t device;
     struct rt_touch_data *data = (struct rt_touch_data *)buf;
diff --git a/bsp/allwinner/libraries/sunxi-hal/hal/source/gmac/hal_geth.c b/bsp/allwinner/libraries/sunxi-hal/hal/source/gmac/hal_geth.c
index e7d56ec00a..d1382f313f 100644
--- a/bsp/allwinner/libraries/sunxi-hal/hal/source/gmac/hal_geth.c
+++ b/bsp/allwinner/libraries/sunxi-hal/hal/source/gmac/hal_geth.c
@@ -743,14 +743,14 @@ static rt_err_t rt_geth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_geth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_geth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     printf("gmac read\n");
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_geth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_geth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     printf("gmac write\n");
     rt_set_errno(-RT_ENOSYS);
diff --git a/bsp/allwinner_tina/drivers/drv_uart.c b/bsp/allwinner_tina/drivers/drv_uart.c
index a2889c598f..ccf327ecde 100644
--- a/bsp/allwinner_tina/drivers/drv_uart.c
+++ b/bsp/allwinner_tina/drivers/drv_uart.c
@@ -40,7 +40,7 @@ static rt_err_t uart_configure(struct rt_serial_device *serial, struct serial_co
 static rt_err_t uart_control(struct rt_serial_device *serial, int cmd, void *arg);
 static int      uart_putc(struct rt_serial_device *serial, char c);
 static int      uart_getc(struct rt_serial_device *serial);
-static rt_size_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+static rt_ssize_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
 
 void     uart_irq_handler(int irqno, void *param);
 
@@ -284,7 +284,7 @@ static int uart_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     return (0);
 }
diff --git a/bsp/amebaz/drivers/drv_uart.c b/bsp/amebaz/drivers/drv_uart.c
index 008fa3bda5..2ad6e12292 100644
--- a/bsp/amebaz/drivers/drv_uart.c
+++ b/bsp/amebaz/drivers/drv_uart.c
@@ -31,7 +31,7 @@ static rt_err_t  ameba_uart_configure    (struct rt_serial_device *serial, struc
 static rt_err_t  ameba_uart_control      (struct rt_serial_device *serial, int cmd, void *arg);
 static int       ameba_uart_putc         (struct rt_serial_device *serial, char c);
 static int       ameba_uart_getc         (struct rt_serial_device *serial);
-static rt_size_t ameba_uart_dma_transmit (struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+static rt_ssize_t ameba_uart_dma_transmit (struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
 
 static void ameba_uart_irq(uint32_t id, SerialIrq event);
 
@@ -118,7 +118,7 @@ static int ameba_uart_getc (struct rt_serial_device *serial)
     return serial_getc(&uart->serial);
 }
 
-static rt_size_t ameba_uart_dma_transmit (struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t ameba_uart_dma_transmit (struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     return (0);
 }
diff --git a/bsp/apm32/libraries/Drivers/drv_eth.c b/bsp/apm32/libraries/Drivers/drv_eth.c
index 08f803f0fb..406fa17b50 100644
--- a/bsp/apm32/libraries/Drivers/drv_eth.c
+++ b/bsp/apm32/libraries/Drivers/drv_eth.c
@@ -412,13 +412,13 @@ static rt_err_t rt_apm32_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_apm32_eth_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_apm32_eth_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_apm32_eth_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_apm32_eth_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/apollo2/board/flash.c b/bsp/apollo2/board/flash.c
index 2d28920daf..5b1480c650 100644
--- a/bsp/apollo2/board/flash.c
+++ b/bsp/apollo2/board/flash.c
@@ -75,7 +75,7 @@ static rt_err_t rt_flash_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t rt_flash_read(rt_device_t dev,
+static rt_ssize_t rt_flash_read(rt_device_t dev,
                                    rt_off_t pos,
                                    void* buffer,
                                    rt_size_t size)
@@ -85,7 +85,7 @@ static rt_size_t rt_flash_read(rt_device_t dev,
     return size;
 }
 
-static rt_size_t rt_flash_write(rt_device_t dev,
+static rt_ssize_t rt_flash_write(rt_device_t dev,
                                     rt_off_t pos,
                                     const void* buffer,
                                     rt_size_t size)
diff --git a/bsp/apollo2/board/rtc.c b/bsp/apollo2/board/rtc.c
index 0eb57aaf84..cbb5dab9d9 100644
--- a/bsp/apollo2/board/rtc.c
+++ b/bsp/apollo2/board/rtc.c
@@ -29,7 +29,7 @@ static rt_err_t rt_rtc_open(rt_device_t dev, rt_uint16_t oflag)
     return RT_EOK;
 }
 
-static rt_size_t rt_rtc_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_rtc_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     return 0;
 }
diff --git a/bsp/at32/libraries/rt_drivers/drv_emac.c b/bsp/at32/libraries/rt_drivers/drv_emac.c
index df72259fda..3b2708b1b9 100644
--- a/bsp/at32/libraries/rt_drivers/drv_emac.c
+++ b/bsp/at32/libraries/rt_drivers/drv_emac.c
@@ -413,14 +413,14 @@ static rt_err_t rt_at32_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_at32_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_at32_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     LOG_D("emac read");
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_at32_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_at32_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     LOG_D("emac write");
     rt_set_errno(-RT_ENOSYS);
diff --git a/bsp/at32/libraries/rt_drivers/drv_usart.c b/bsp/at32/libraries/rt_drivers/drv_usart.c
index 9d2adbb384..7a327d61f3 100644
--- a/bsp/at32/libraries/rt_drivers/drv_usart.c
+++ b/bsp/at32/libraries/rt_drivers/drv_usart.c
@@ -333,7 +333,7 @@ static void at32_dma_config(struct rt_serial_device *serial, rt_ubase_t flag)
     nvic_irq_enable(instance->irqn, 1, 0);
 }
 
-static rt_size_t at32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t at32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     struct at32_uart *instance;
     instance = (struct at32_uart *) serial->parent.user_data;
diff --git a/bsp/at91/at91sam9260/drivers/macb.c b/bsp/at91/at91sam9260/drivers/macb.c
index 702d7e04a4..e0e3bda2ea 100644
--- a/bsp/at91/at91sam9260/drivers/macb.c
+++ b/bsp/at91/at91sam9260/drivers/macb.c
@@ -514,13 +514,13 @@ static rt_err_t rt_macb_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_macb_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_macb_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_macb_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_macb_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/at91/at91sam9g45/drivers/macb.c b/bsp/at91/at91sam9g45/drivers/macb.c
index 8a300725c3..8065b4afcb 100644
--- a/bsp/at91/at91sam9g45/drivers/macb.c
+++ b/bsp/at91/at91sam9g45/drivers/macb.c
@@ -514,13 +514,13 @@ static rt_err_t rt_macb_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_macb_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_macb_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_macb_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_macb_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/bluetrum/libraries/hal_drivers/drv_usart.c b/bsp/bluetrum/libraries/hal_drivers/drv_usart.c
index ab296274c5..ea190324ca 100644
--- a/bsp/bluetrum/libraries/hal_drivers/drv_usart.c
+++ b/bsp/bluetrum/libraries/hal_drivers/drv_usart.c
@@ -209,7 +209,7 @@ static int ab32_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t ab32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t ab32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     return -1;
 }
diff --git a/bsp/dm365/drivers/davinci_emac.c b/bsp/dm365/drivers/davinci_emac.c
index b164bf7aaa..f294727c56 100644
--- a/bsp/dm365/drivers/davinci_emac.c
+++ b/bsp/dm365/drivers/davinci_emac.c
@@ -1585,16 +1585,14 @@ static rt_err_t rt_davinci_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_davinci_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_davinci_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-    return 0;
+    return -RT_ENOSYS;
 }
 
-static rt_size_t rt_davinci_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_davinci_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-    return 0;
+    return -RT_ENOSYS;
 }
 
 static rt_err_t rt_davinci_emac_control(rt_device_t dev, int cmd, void *args)
diff --git a/bsp/efm32/drv_ethernet.c b/bsp/efm32/drv_ethernet.c
index 57d88cab54..7792f20158 100644
--- a/bsp/efm32/drv_ethernet.c
+++ b/bsp/efm32/drv_ethernet.c
@@ -606,7 +606,7 @@ static rt_err_t efm_eth_close(rt_device_t dev)
  * @return
  *   Number of read bytes
  ******************************************************************************/
-static rt_size_t efm_eth_read(
+static rt_ssize_t efm_eth_read(
     rt_device_t     dev,
     rt_off_t        pos,
     void            *buffer,
@@ -639,7 +639,7 @@ static rt_size_t efm_eth_read(
  * @return
  *   Number of written bytes
  ******************************************************************************/
-static rt_size_t efm_eth_write (
+static rt_ssize_t efm_eth_write (
     rt_device_t     dev,
     rt_off_t        pos,
     const void      *buffer,
diff --git a/bsp/efm32/drv_iic.c b/bsp/efm32/drv_iic.c
index acb7d09375..4bae9ae94a 100644
--- a/bsp/efm32/drv_iic.c
+++ b/bsp/efm32/drv_iic.c
@@ -182,7 +182,7 @@ static rt_err_t rt_iic_close(rt_device_t dev)
  * @return
  *   Error code
  ******************************************************************************/
-static rt_size_t rt_iic_read (
+static rt_ssize_t rt_iic_read (
     rt_device_t     dev,
     rt_off_t        pos,
     void*           buffer,
@@ -343,7 +343,7 @@ static rt_size_t rt_iic_read (
  * @return
  *   Error code
  ******************************************************************************/
-static rt_size_t rt_iic_write (
+static rt_ssize_t rt_iic_write (
     rt_device_t     dev,
     rt_off_t        pos,
     const void*     buffer,
diff --git a/bsp/efm32/drv_leuart.c b/bsp/efm32/drv_leuart.c
index 06aeb9e25e..bf1720b8ad 100644
--- a/bsp/efm32/drv_leuart.c
+++ b/bsp/efm32/drv_leuart.c
@@ -247,7 +247,7 @@ static rt_err_t rt_leuart_close(rt_device_t dev)
  * @return
  *   Number of read bytes
  ******************************************************************************/
-static rt_size_t rt_leuart_read (
+static rt_ssize_t rt_leuart_read (
     rt_device_t     dev,
     rt_off_t        pos,
     void            *buffer,
@@ -372,7 +372,7 @@ static rt_size_t rt_leuart_read (
  * @return
  *   Number of written bytes
  ******************************************************************************/
-static rt_size_t rt_leuart_write (
+static rt_ssize_t rt_leuart_write (
     rt_device_t     dev,
     rt_off_t        pos,
     const void*     buffer,
diff --git a/bsp/efm32/drv_rtc.c b/bsp/efm32/drv_rtc.c
index 4956d76953..20acb19666 100644
--- a/bsp/efm32/drv_rtc.c
+++ b/bsp/efm32/drv_rtc.c
@@ -49,7 +49,7 @@ static rt_err_t rt_rtc_open(rt_device_t dev, rt_uint16_t oflag)
     return RT_EOK;
 }
 
-static rt_size_t rt_rtc_read(
+static rt_ssize_t rt_rtc_read(
     rt_device_t     dev,
     rt_off_t        pos,
     void*           buffer,
diff --git a/bsp/efm32/drv_sdcard.c b/bsp/efm32/drv_sdcard.c
index 593bc2b697..f58c126f89 100644
--- a/bsp/efm32/drv_sdcard.c
+++ b/bsp/efm32/drv_sdcard.c
@@ -136,7 +136,7 @@ static void efm_spiSd_speed(rt_uint8_t level)
  * @return
  *   Number of read bytes
  ******************************************************************************/
-static rt_size_t efm_spiSd_read(void *buffer, rt_size_t size)
+static rt_ssize_t efm_spiSd_read(void *buffer, rt_size_t size)
 {
     RT_ASSERT(spi != RT_NULL);
 
@@ -807,7 +807,7 @@ static rt_err_t rt_spiSd_close(rt_device_t dev)
  * @return
  *   Number of read sectors
  ******************************************************************************/
-static rt_size_t rt_spiSd_read(
+static rt_ssize_t rt_spiSd_read(
     rt_device_t     dev,
     rt_off_t        sector,
     void            *buffer,
@@ -897,7 +897,7 @@ static rt_size_t rt_spiSd_read(
  * @return
  *   Number of written sectors
  ******************************************************************************/
-static rt_size_t rt_spiSd_write (
+static rt_ssize_t rt_spiSd_write (
     rt_device_t     dev,
     rt_off_t        sector,
     const void      *buffer,
diff --git a/bsp/efm32/drv_usart.c b/bsp/efm32/drv_usart.c
index edf0643564..1c97556eac 100644
--- a/bsp/efm32/drv_usart.c
+++ b/bsp/efm32/drv_usart.c
@@ -354,7 +354,7 @@ static rt_err_t rt_usart_close(rt_device_t dev)
  * @return
  *  Number of read bytes
  ******************************************************************************/
-static rt_size_t rt_usart_read (
+static rt_ssize_t rt_usart_read (
     rt_device_t     dev,
     rt_off_t        pos,
     void            *buffer,
@@ -550,7 +550,7 @@ static rt_size_t rt_usart_read (
  * @return
  *   Number of written bytes
  ******************************************************************************/
-static rt_size_t rt_usart_write (
+static rt_ssize_t rt_usart_write (
     rt_device_t     dev,
     rt_off_t        pos,
     const void*     buffer,
diff --git a/bsp/essemi/es32f0654/drivers/drv_i2c.c b/bsp/essemi/es32f0654/drivers/drv_i2c.c
index 96375d31f6..a1ae7fb71f 100644
--- a/bsp/essemi/es32f0654/drivers/drv_i2c.c
+++ b/bsp/essemi/es32f0654/drivers/drv_i2c.c
@@ -106,7 +106,7 @@ static void _i2c_init(void)
 #endif
 }
 
-static rt_size_t es32f0_master_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t es32f0_master_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num)
 {
diff --git a/bsp/essemi/es32f369x/drivers/drv_i2c.c b/bsp/essemi/es32f369x/drivers/drv_i2c.c
index 8f905e314f..dfce73e3a4 100644
--- a/bsp/essemi/es32f369x/drivers/drv_i2c.c
+++ b/bsp/essemi/es32f369x/drivers/drv_i2c.c
@@ -265,7 +265,7 @@ SUCCESS:
     return OK;
 }
 
-static rt_size_t es32f3_master_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t es32f3_master_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num)
 {
diff --git a/bsp/essemi/es32f369x/drivers/drv_uart.c b/bsp/essemi/es32f369x/drivers/drv_uart.c
index 1a738447ff..dfb4ad0f9c 100644
--- a/bsp/essemi/es32f369x/drivers/drv_uart.c
+++ b/bsp/essemi/es32f369x/drivers/drv_uart.c
@@ -721,7 +721,7 @@ static int es32f3x_getc(struct rt_serial_device *serial)
 /**
  * DMA transmit
  */
-static rt_size_t es32f3x_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t es32f3x_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     struct es32_uart *uart;
 
diff --git a/bsp/frdm-k64f/board/drv_emac.c b/bsp/frdm-k64f/board/drv_emac.c
index 87b6c6c34d..94ce23e418 100644
--- a/bsp/frdm-k64f/board/drv_emac.c
+++ b/bsp/frdm-k64f/board/drv_emac.c
@@ -229,16 +229,14 @@ static rt_err_t k64_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t k64_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t k64_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-    return 0;
+    return -RT_ENOSYS;
 }
 
-static rt_size_t k64_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t k64_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-    return 0;
+    return -RT_ENOSYS;
 }
 
 static rt_err_t k64_emac_control(rt_device_t dev, int cmd, void *args)
diff --git a/bsp/ft2004/drivers/drv_eth.c b/bsp/ft2004/drivers/drv_eth.c
index e7148631e4..256ce42e29 100644
--- a/bsp/ft2004/drivers/drv_eth.c
+++ b/bsp/ft2004/drivers/drv_eth.c
@@ -250,14 +250,14 @@ static rt_err_t rt_ft2004_gmac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_ft2004_gmac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_ft2004_gmac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     LOG_D("gmac read");
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_ft2004_gmac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_ft2004_gmac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     LOG_D("gmac write");
     rt_set_errno(-RT_ENOSYS);
diff --git a/bsp/ft32/libraries/Drivers/drv_usart.c b/bsp/ft32/libraries/Drivers/drv_usart.c
index 1fe34e3763..ee308c946c 100644
--- a/bsp/ft32/libraries/Drivers/drv_usart.c
+++ b/bsp/ft32/libraries/Drivers/drv_usart.c
@@ -305,7 +305,7 @@ static int ft32_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t ft32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t ft32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     RT_ASSERT(serial != RT_NULL);
     RT_ASSERT(buf != RT_NULL);
diff --git a/bsp/fujitsu/mb9x/mb9bf506r/drivers/nand.c b/bsp/fujitsu/mb9x/mb9bf506r/drivers/nand.c
index 1c03120d14..0eb9b418a4 100644
--- a/bsp/fujitsu/mb9x/mb9bf506r/drivers/nand.c
+++ b/bsp/fujitsu/mb9x/mb9bf506r/drivers/nand.c
@@ -358,7 +358,7 @@ static rt_err_t rt_nand_close(rt_device_t dev)
 }
 
 /* nand device read */
-static rt_size_t rt_nand_read (rt_device_t dev, rt_off_t pos, void* buffer,
+static rt_ssize_t rt_nand_read (rt_device_t dev, rt_off_t pos, void* buffer,
                                rt_size_t size)
 {
     rt_ubase_t block;           /* block of position */
@@ -456,7 +456,7 @@ static int rt_nand_eraseblock_writepage(struct rt_device_nand* nand,
 }
 
 /* nand device write */
-static rt_size_t rt_nand_write (rt_device_t dev, rt_off_t pos,
+static rt_ssize_t rt_nand_write (rt_device_t dev, rt_off_t pos,
                                 const void* buffer, rt_size_t size)
 {
     rt_ubase_t block, page;
diff --git a/bsp/fujitsu/mb9x/mb9bf568r/drivers/led.c b/bsp/fujitsu/mb9x/mb9bf568r/drivers/led.c
index db80b56fd0..9e138d6f0b 100644
--- a/bsp/fujitsu/mb9x/mb9bf568r/drivers/led.c
+++ b/bsp/fujitsu/mb9x/mb9bf568r/drivers/led.c
@@ -72,7 +72,7 @@ static rt_err_t rt_led_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_led_read (rt_device_t dev, rt_off_t pos, void* buffer,
+static rt_ssize_t rt_led_read (rt_device_t dev, rt_off_t pos, void* buffer,
                               rt_size_t size)
 {
     rt_ubase_t index = 0;
@@ -97,7 +97,7 @@ static rt_size_t rt_led_read (rt_device_t dev, rt_off_t pos, void* buffer,
     return index;
 }
 
-static rt_size_t rt_led_write (rt_device_t dev, rt_off_t pos,
+static rt_ssize_t rt_led_write (rt_device_t dev, rt_off_t pos,
                                const void* buffer, rt_size_t size)
 {
     rt_ubase_t index = 0;
diff --git a/bsp/fujitsu/mb9x/mb9bf568r/drivers/serial.c b/bsp/fujitsu/mb9x/mb9bf568r/drivers/serial.c
index 6c3a132216..305424a2a0 100644
--- a/bsp/fujitsu/mb9x/mb9bf568r/drivers/serial.c
+++ b/bsp/fujitsu/mb9x/mb9bf568r/drivers/serial.c
@@ -105,7 +105,7 @@ static rt_err_t rt_serial_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer,
+static rt_ssize_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer,
                                  rt_size_t size)
 {
     rt_uint8_t* ptr;
@@ -164,7 +164,7 @@ static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer,
     return (rt_uint32_t)ptr - (rt_uint32_t)buffer;
 }
 
-static rt_size_t rt_serial_write (rt_device_t dev, rt_off_t pos,
+static rt_ssize_t rt_serial_write (rt_device_t dev, rt_off_t pos,
                                   const void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
diff --git a/bsp/fujitsu/mb9x/mb9bf618s/drivers/led.c b/bsp/fujitsu/mb9x/mb9bf618s/drivers/led.c
index bfad9947e7..d26ab4f333 100644
--- a/bsp/fujitsu/mb9x/mb9bf618s/drivers/led.c
+++ b/bsp/fujitsu/mb9x/mb9bf618s/drivers/led.c
@@ -75,7 +75,7 @@ static rt_err_t rt_led_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_led_read (rt_device_t dev, rt_off_t pos, void* buffer,
+static rt_ssize_t rt_led_read (rt_device_t dev, rt_off_t pos, void* buffer,
                               rt_size_t size)
 {
     rt_ubase_t index = 0;
@@ -100,7 +100,7 @@ static rt_size_t rt_led_read (rt_device_t dev, rt_off_t pos, void* buffer,
     return index;
 }
 
-static rt_size_t rt_led_write (rt_device_t dev, rt_off_t pos,
+static rt_ssize_t rt_led_write (rt_device_t dev, rt_off_t pos,
                                const void* buffer, rt_size_t size)
 {
     rt_ubase_t index = 0;
diff --git a/bsp/fujitsu/mb9x/mb9bf618s/drivers/serial.c b/bsp/fujitsu/mb9x/mb9bf618s/drivers/serial.c
index 79279e79e5..c0fd1ac1e6 100644
--- a/bsp/fujitsu/mb9x/mb9bf618s/drivers/serial.c
+++ b/bsp/fujitsu/mb9x/mb9bf618s/drivers/serial.c
@@ -105,7 +105,7 @@ static rt_err_t rt_serial_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer,
+static rt_ssize_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer,
                                  rt_size_t size)
 {
     rt_uint8_t* ptr;
@@ -164,7 +164,7 @@ static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer,
     return (rt_uint32_t)ptr - (rt_uint32_t)buffer;
 }
 
-static rt_size_t rt_serial_write (rt_device_t dev, rt_off_t pos,
+static rt_ssize_t rt_serial_write (rt_device_t dev, rt_off_t pos,
                                   const void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
diff --git a/bsp/gd32/arm/libraries/gd32_drivers/drv_sdio.c b/bsp/gd32/arm/libraries/gd32_drivers/drv_sdio.c
index be13acb872..d7d408ac1d 100644
--- a/bsp/gd32/arm/libraries/gd32_drivers/drv_sdio.c
+++ b/bsp/gd32/arm/libraries/gd32_drivers/drv_sdio.c
@@ -232,7 +232,7 @@ static rt_err_t rt_sdcard_close(rt_device_t dev)
 }
 
 static uint32_t dma_buffer[SECTOR_SIZE/sizeof(uint32_t)];
-static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
 
@@ -283,7 +283,7 @@ static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_
     }
 }
 
-static rt_size_t rt_sdcard_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
 #define WR_RETRY_TIMES 2
 
diff --git a/bsp/gd32105c-eval/drivers/drv_i2c.c b/bsp/gd32105c-eval/drivers/drv_i2c.c
index 6d3d2cedcc..1f442d6afb 100644
--- a/bsp/gd32105c-eval/drivers/drv_i2c.c
+++ b/bsp/gd32105c-eval/drivers/drv_i2c.c
@@ -225,7 +225,7 @@ static int gd32_i2c_write(rt_uint32_t i2c_periph, uint16_t slave_address, uint8_
     return 0;
 }
 
-static rt_size_t gd32_i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t gd32_i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
     rt_uint32_t i;
diff --git a/bsp/gd32107c-eval/drivers/drv_i2c.c b/bsp/gd32107c-eval/drivers/drv_i2c.c
index 6d3d2cedcc..1f442d6afb 100644
--- a/bsp/gd32107c-eval/drivers/drv_i2c.c
+++ b/bsp/gd32107c-eval/drivers/drv_i2c.c
@@ -225,7 +225,7 @@ static int gd32_i2c_write(rt_uint32_t i2c_periph, uint16_t slave_address, uint8_
     return 0;
 }
 
-static rt_size_t gd32_i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t gd32_i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
     rt_uint32_t i;
diff --git a/bsp/gd32303e-eval/drivers/drv_i2c.c b/bsp/gd32303e-eval/drivers/drv_i2c.c
index e7587618fe..4f080d2c83 100644
--- a/bsp/gd32303e-eval/drivers/drv_i2c.c
+++ b/bsp/gd32303e-eval/drivers/drv_i2c.c
@@ -226,7 +226,7 @@ static int gd32_i2c_write(rt_uint32_t i2c_periph, uint16_t slave_address, uint8_
     return 0;
 }
 
-static rt_size_t gd32_i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t gd32_i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
     rt_uint32_t i;
diff --git a/bsp/gd32450z-eval/drivers/drv_enet.c b/bsp/gd32450z-eval/drivers/drv_enet.c
index f461b50fba..b37146e3c3 100644
--- a/bsp/gd32450z-eval/drivers/drv_enet.c
+++ b/bsp/gd32450z-eval/drivers/drv_enet.c
@@ -200,16 +200,14 @@ static rt_err_t gd32_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t gd32_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t gd32_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-    return 0;
+    return -RT_ENOSYS;
 }
 
-static rt_size_t gd32_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t gd32_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-    return 0;
+    return -RT_ENOSYS;
 }
 
 static rt_err_t gd32_emac_control(rt_device_t dev, int cmd, void *args)
diff --git a/bsp/gd32e230k-start/drivers/drv_i2c.c b/bsp/gd32e230k-start/drivers/drv_i2c.c
index 62cd4eb973..cad5cd4b08 100644
--- a/bsp/gd32e230k-start/drivers/drv_i2c.c
+++ b/bsp/gd32e230k-start/drivers/drv_i2c.c
@@ -227,7 +227,7 @@ static int gd32_i2c_write(rt_uint32_t i2c_periph, uint16_t slave_address, uint8_
     return 0;
 }
 
-static rt_size_t gd32_i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t gd32_i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
     rt_uint32_t i;
diff --git a/bsp/hc32/libraries/hc32_drivers/drv_eth.c b/bsp/hc32/libraries/hc32_drivers/drv_eth.c
index 9e687621f0..da5c9aace1 100644
--- a/bsp/hc32/libraries/hc32_drivers/drv_eth.c
+++ b/bsp/hc32/libraries/hc32_drivers/drv_eth.c
@@ -178,14 +178,14 @@ static rt_err_t rt_hc32_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_hc32_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_hc32_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     LOG_D("eth read");
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_hc32_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_hc32_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     LOG_D("eth write");
     rt_set_errno(-RT_ENOSYS);
diff --git a/bsp/hc32/libraries/hc32_drivers/drv_usart.c b/bsp/hc32/libraries/hc32_drivers/drv_usart.c
index a960418db5..82f2a637a2 100644
--- a/bsp/hc32/libraries/hc32_drivers/drv_usart.c
+++ b/bsp/hc32/libraries/hc32_drivers/drv_usart.c
@@ -374,7 +374,7 @@ static int hc32_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t hc32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t hc32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
 #ifdef RT_SERIAL_USING_DMA
     struct hc32_uart *uart;
diff --git a/bsp/hc32l136/drivers/drv_usart.c b/bsp/hc32l136/drivers/drv_usart.c
index 7f81374dbb..d5904a63d6 100644
--- a/bsp/hc32l136/drivers/drv_usart.c
+++ b/bsp/hc32l136/drivers/drv_usart.c
@@ -383,7 +383,7 @@ static int hc32_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t hc32_dma_transmit(struct rt_serial_device *serial,
+static rt_ssize_t hc32_dma_transmit(struct rt_serial_device *serial,
                                    rt_uint8_t *buf,
                                    rt_size_t size,
                                    int direction)
diff --git a/bsp/hpmicro/hpm6750evk/board/eth_phy_port.c b/bsp/hpmicro/hpm6750evk/board/eth_phy_port.c
index e229bf41d8..68c4f46406 100644
--- a/bsp/hpmicro/hpm6750evk/board/eth_phy_port.c
+++ b/bsp/hpmicro/hpm6750evk/board/eth_phy_port.c
@@ -101,14 +101,14 @@ static rt_phy_status phy_init(void *object, rt_uint32_t phy_addr, rt_uint32_t sr
     return PHY_STATUS_OK;
 }
 
-static rt_size_t phy_read(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
+static rt_ssize_t phy_read(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
 {
     *(uint16_t *)data = enet_read_phy(((struct rt_mdio_bus *)bus)->hw_obj, addr, reg);
 
     return size;
 }
 
-static rt_size_t phy_write(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
+static rt_ssize_t phy_write(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
 {
     enet_write_phy(((struct rt_mdio_bus *)bus)->hw_obj, addr, reg,  *(uint16_t *)data);
 
diff --git a/bsp/hpmicro/hpm6750evkmini/board/eth_phy_port.c b/bsp/hpmicro/hpm6750evkmini/board/eth_phy_port.c
index 665541daec..c5b6b55f12 100644
--- a/bsp/hpmicro/hpm6750evkmini/board/eth_phy_port.c
+++ b/bsp/hpmicro/hpm6750evkmini/board/eth_phy_port.c
@@ -101,14 +101,14 @@ static rt_phy_status phy_init(void *object, rt_uint32_t phy_addr, rt_uint32_t sr
     return PHY_STATUS_OK;
 }
 
-static rt_size_t phy_read(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
+static rt_ssize_t phy_read(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
 {
     *(uint16_t *)data = enet_read_phy(((struct rt_mdio_bus *)bus)->hw_obj, addr, reg);
 
     return size;
 }
 
-static rt_size_t phy_write(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
+static rt_ssize_t phy_write(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
 {
     enet_write_phy(((struct rt_mdio_bus *)bus)->hw_obj, addr, reg,  *(uint16_t *)data);
 
diff --git a/bsp/hpmicro/libraries/drivers/drv_dao.c b/bsp/hpmicro/libraries/drivers/drv_dao.c
index 01cdf69ffe..3ba9096395 100644
--- a/bsp/hpmicro/libraries/drivers/drv_dao.c
+++ b/bsp/hpmicro/libraries/drivers/drv_dao.c
@@ -214,7 +214,7 @@ static rt_err_t hpm_dao_stop(struct rt_audio_device* audio, int stream)
     return RT_EOK;
 }
 
-static rt_size_t hpm_dao_transmit(struct rt_audio_device* audio, const void* writeBuf, void* readBuf, rt_size_t size)
+static rt_ssize_t hpm_dao_transmit(struct rt_audio_device* audio, const void* writeBuf, void* readBuf, rt_size_t size)
 {
     RT_ASSERT(audio != RT_NULL);
 
diff --git a/bsp/hpmicro/libraries/drivers/drv_enet.c b/bsp/hpmicro/libraries/drivers/drv_enet.c
index c9e4819ebb..860a867682 100644
--- a/bsp/hpmicro/libraries/drivers/drv_enet.c
+++ b/bsp/hpmicro/libraries/drivers/drv_enet.c
@@ -196,12 +196,12 @@ static rt_err_t rt_hpm_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_hpm_eth_read(rt_device_t dev, rt_off_t pos, void * buffer, rt_size_t size)
+static rt_ssize_t rt_hpm_eth_read(rt_device_t dev, rt_off_t pos, void * buffer, rt_size_t size)
 {
     return 0;
 }
 
-static rt_size_t rt_hpm_eth_write(rt_device_t dev, rt_off_t pos, const void * buffer, rt_size_t size)
+static rt_ssize_t rt_hpm_eth_write(rt_device_t dev, rt_off_t pos, const void * buffer, rt_size_t size)
 {
     return 0;
 }
diff --git a/bsp/hpmicro/libraries/drivers/drv_i2c.c b/bsp/hpmicro/libraries/drivers/drv_i2c.c
index 4d83707262..4549d81c0a 100644
--- a/bsp/hpmicro/libraries/drivers/drv_i2c.c
+++ b/bsp/hpmicro/libraries/drivers/drv_i2c.c
@@ -55,7 +55,7 @@ static struct hpm_i2c hpm_i2cs[] =
 #endif
 };
 
-static rt_size_t hpm_i2c_master_transfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num);
+static rt_ssize_t hpm_i2c_master_transfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num);
 
 
 struct rt_i2c_bus_device_ops hpm_i2c_ops =
@@ -65,7 +65,7 @@ struct rt_i2c_bus_device_ops hpm_i2c_ops =
     RT_NULL
 };
 
-static rt_size_t hpm_i2c_master_transfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t hpm_i2c_master_transfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     RT_ASSERT(bus != RT_NULL);
     RT_ASSERT(msgs != RT_NULL);
diff --git a/bsp/hpmicro/libraries/drivers/drv_i2s.c b/bsp/hpmicro/libraries/drivers/drv_i2s.c
index 5312ee0a10..bac0bf677f 100644
--- a/bsp/hpmicro/libraries/drivers/drv_i2s.c
+++ b/bsp/hpmicro/libraries/drivers/drv_i2s.c
@@ -24,7 +24,7 @@
 #include "drv_i2s.h"
 #include "drivers/audio.h"
 
-static rt_size_t hpm_i2s_transmit(struct rt_audio_device* audio, const void* writeBuf, void* readBuf, rt_size_t size);
+static rt_ssize_t hpm_i2s_transmit(struct rt_audio_device* audio, const void* writeBuf, void* readBuf, rt_size_t size);
 
 struct hpm_i2s
 {
@@ -462,7 +462,7 @@ static rt_err_t hpm_i2s_stop(struct rt_audio_device* audio, int stream)
     return RT_EOK;
 }
 
-static rt_size_t hpm_i2s_transmit(struct rt_audio_device* audio, const void* writeBuf, void* readBuf, rt_size_t size)
+static rt_ssize_t hpm_i2s_transmit(struct rt_audio_device* audio, const void* writeBuf, void* readBuf, rt_size_t size)
 {
     RT_ASSERT(audio != RT_NULL);
     struct hpm_i2s* hpm_audio = (struct hpm_i2s*)audio->parent.user_data;
diff --git a/bsp/hpmicro/libraries/drivers/drv_rtc.c b/bsp/hpmicro/libraries/drivers/drv_rtc.c
index f701d71195..114ad7a07b 100644
--- a/bsp/hpmicro/libraries/drivers/drv_rtc.c
+++ b/bsp/hpmicro/libraries/drivers/drv_rtc.c
@@ -25,8 +25,8 @@
 static rt_err_t hpm_rtc_init(rt_device_t dev);
 static rt_err_t hpm_rtc_open(rt_device_t dev, rt_uint16_t oflag);
 static rt_err_t hpm_rtc_close(rt_device_t dev);
-static rt_size_t hpm_rtc_read(rt_device_t dev, rt_off_t pos, void *buf, rt_size_t size);
-static rt_size_t hpm_rtc_write(rt_device_t dev, rt_off_t pos, const void *buf, rt_size_t size);
+static rt_ssize_t hpm_rtc_read(rt_device_t dev, rt_off_t pos, void *buf, rt_size_t size);
+static rt_ssize_t hpm_rtc_write(rt_device_t dev, rt_off_t pos, const void *buf, rt_size_t size);
 static rt_err_t hpm_rtc_control(rt_device_t dev, int cmd, void *args);
 
 static time_t hpm_rtc_get_timestamp(void);
@@ -64,11 +64,11 @@ static rt_err_t hpm_rtc_close(rt_device_t dev)
 {
     return RT_EOK;
 }
-static rt_size_t hpm_rtc_read(rt_device_t dev, rt_off_t pos, void *buf, rt_size_t size)
+static rt_ssize_t hpm_rtc_read(rt_device_t dev, rt_off_t pos, void *buf, rt_size_t size)
 {
     return 0;
 }
-static rt_size_t hpm_rtc_write(rt_device_t dev, rt_off_t pos, const void *buf, rt_size_t size)
+static rt_ssize_t hpm_rtc_write(rt_device_t dev, rt_off_t pos, const void *buf, rt_size_t size)
 {
     return 0;
 }
diff --git a/bsp/hpmicro/libraries/drivers/drv_uart_v2.c b/bsp/hpmicro/libraries/drivers/drv_uart_v2.c
index ce82dfb0cb..6f4f012cb3 100644
--- a/bsp/hpmicro/libraries/drivers/drv_uart_v2.c
+++ b/bsp/hpmicro/libraries/drivers/drv_uart_v2.c
@@ -864,7 +864,7 @@ static int hpm_uart_getc(struct rt_serial_device *serial)
     return result;
 }
 
-static rt_size_t hpm_uart_transmit(struct rt_serial_device *serial,
+static rt_ssize_t hpm_uart_transmit(struct rt_serial_device *serial,
                                     rt_uint8_t *buf,
                                     rt_size_t size,
                                     rt_uint32_t tx_flag)
diff --git a/bsp/hpmicro/libraries/drivers/drv_usb.c b/bsp/hpmicro/libraries/drivers/drv_usb.c
index 946a9f3a1a..1d00550e0b 100644
--- a/bsp/hpmicro/libraries/drivers/drv_usb.c
+++ b/bsp/hpmicro/libraries/drivers/drv_usb.c
@@ -13,8 +13,8 @@
 /* Definition of logic unit number for each drive */
 #define LUN_USB     (0U)    /* lun 0 of usb drive */
 
-static rt_size_t hpm_usb_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-static rt_size_t hpm_usb_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+static rt_ssize_t hpm_usb_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+static rt_ssize_t hpm_usb_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 rt_err_t  hpm_usb_control(rt_device_t dev, int cmd, void *args);
 
 rt_uint8_t usb_dev_addr;
@@ -50,7 +50,7 @@ void hpm_usb_set_addr(uint8_t dev_addr)
     usb_dev_addr = dev_addr;
 }
 
-static rt_size_t hpm_usb_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t hpm_usb_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_bool_t result;
 
@@ -63,7 +63,7 @@ static rt_size_t hpm_usb_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_si
     return result ? size : 0;
 }
 
-static rt_size_t hpm_usb_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t hpm_usb_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     bool result;
 
diff --git a/bsp/imx6sx/cortex-a9/drivers/emac_drv.c b/bsp/imx6sx/cortex-a9/drivers/emac_drv.c
index ff8a579435..80d2a95618 100644
--- a/bsp/imx6sx/cortex-a9/drivers/emac_drv.c
+++ b/bsp/imx6sx/cortex-a9/drivers/emac_drv.c
@@ -116,13 +116,13 @@ static rt_err_t imx_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t imx_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t imx_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t imx_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t imx_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/imxrt/libraries/drivers/drv_eth.c b/bsp/imxrt/libraries/drivers/drv_eth.c
index df22eab181..7454fd18f7 100644
--- a/bsp/imxrt/libraries/drivers/drv_eth.c
+++ b/bsp/imxrt/libraries/drivers/drv_eth.c
@@ -489,14 +489,14 @@ static rt_err_t rt_imxrt_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_imxrt_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_imxrt_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     dbg_log(DBG_LOG, "rt_imxrt_eth_read...\n");
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_imxrt_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_imxrt_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     dbg_log(DBG_LOG, "rt_imxrt_eth_write...\n");
     rt_set_errno(-RT_ENOSYS);
diff --git a/bsp/imxrt/libraries/drivers/drv_i2c.c b/bsp/imxrt/libraries/drivers/drv_i2c.c
index ed16dee061..6f66a68451 100644
--- a/bsp/imxrt/libraries/drivers/drv_i2c.c
+++ b/bsp/imxrt/libraries/drivers/drv_i2c.c
@@ -134,10 +134,10 @@ static struct imxrt_i2c_bus lpi2c6 =
 
 #if (defined(BSP_USING_I2C1) || defined(BSP_USING_I2C2) || defined(BSP_USING_I2C3) || defined(BSP_USING_I2C4) ||defined(BSP_USING_I2C5) || defined(BSP_USING_I2C6))
 
-static rt_size_t imxrt_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t imxrt_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num);
-static rt_size_t imxrt_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t imxrt_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num);
 static rt_err_t imxrt_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -249,7 +249,7 @@ static status_t LPI2C_MasterWaitForTxFifoAllEmpty(LPI2C_Type *base)
     return kStatus_Success;
 }
 
-static rt_size_t imxrt_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t imxrt_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num)
 {
@@ -365,7 +365,7 @@ static rt_size_t imxrt_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
     return i;
 }
 
-static rt_size_t imxrt_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t imxrt_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num)
 {
diff --git a/bsp/imxrt/libraries/drivers/drv_mdio.c b/bsp/imxrt/libraries/drivers/drv_mdio.c
index 354b982280..98f8d3a5c8 100644
--- a/bsp/imxrt/libraries/drivers/drv_mdio.c
+++ b/bsp/imxrt/libraries/drivers/drv_mdio.c
@@ -51,7 +51,7 @@ static rt_bool_t rt_hw_mdio_init(void *bus, rt_uint32_t src_clock_hz)
     return RT_TRUE;
 }
 
-static rt_size_t rt_hw_mdio_read(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
+static rt_ssize_t rt_hw_mdio_read(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
 {
     RT_ASSERT(data);
     struct rt_mdio_bus *bus_obj = (struct rt_mdio_bus *)bus;
@@ -96,7 +96,7 @@ static rt_size_t rt_hw_mdio_read(void *bus, rt_uint32_t addr, rt_uint32_t reg, v
 }
 
 
-static rt_size_t rt_hw_mdio_write(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
+static rt_ssize_t rt_hw_mdio_write(void *bus, rt_uint32_t addr, rt_uint32_t reg, void *data, rt_uint32_t size)
 {
     struct rt_mdio_bus *bus_obj = (struct rt_mdio_bus *)bus;
     uint32_t counter;
diff --git a/bsp/imxrt/libraries/drivers/drv_rtc.c b/bsp/imxrt/libraries/drivers/drv_rtc.c
index 4a95b496d0..c7e9ad58d2 100644
--- a/bsp/imxrt/libraries/drivers/drv_rtc.c
+++ b/bsp/imxrt/libraries/drivers/drv_rtc.c
@@ -103,12 +103,12 @@ static rt_err_t imxrt_hp_rtc_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t imxrt_hp_rtc_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t imxrt_hp_rtc_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     return -RT_EINVAL;
 }
 
-static rt_size_t imxrt_hp_rtc_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t imxrt_hp_rtc_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     return -RT_EINVAL;
 }
diff --git a/bsp/imxrt/libraries/drivers/drv_sai.c b/bsp/imxrt/libraries/drivers/drv_sai.c
index 166498cae3..5dcdf52bfc 100644
--- a/bsp/imxrt/libraries/drivers/drv_sai.c
+++ b/bsp/imxrt/libraries/drivers/drv_sai.c
@@ -504,7 +504,7 @@ static rt_err_t imxrt_payer_stop(struct rt_audio_device* audio, int stream)
     return RT_EOK;
 
 }
-static rt_size_t imxrt_payer_transmit(struct rt_audio_device* audio, const void* writeBuf, void* readBuf, rt_size_t size)
+static rt_ssize_t imxrt_payer_transmit(struct rt_audio_device* audio, const void* writeBuf, void* readBuf, rt_size_t size)
 {
     RT_ASSERT(audio != RT_NULL);
 #if defined (BSP_USING_AUDIO_RECORD)
diff --git a/bsp/imxrt/libraries/drivers/drv_usbd.c b/bsp/imxrt/libraries/drivers/drv_usbd.c
index 49f47e4d1d..547e6c5988 100644
--- a/bsp/imxrt/libraries/drivers/drv_usbd.c
+++ b/bsp/imxrt/libraries/drivers/drv_usbd.c
@@ -152,7 +152,7 @@ static rt_err_t _ehci0_ep_disable(uep_t ep)
     return RT_EOK;
 }
 
-static rt_size_t _ehci0_ep_read(rt_uint8_t address, void *buffer)
+static rt_ssize_t _ehci0_ep_read(rt_uint8_t address, void *buffer)
 {
     rt_size_t size = 0;
 
@@ -161,13 +161,13 @@ static rt_size_t _ehci0_ep_read(rt_uint8_t address, void *buffer)
     return size;
 }
 
-static rt_size_t _ehci0_ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ehci0_ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     USB_DeviceRecvRequest(ehci0_handle, address, buffer, size);
     return size;
 }
 
-static rt_size_t _ehci0_ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ehci0_ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     USB_DeviceSendRequest(ehci0_handle, address, buffer, size);
     return size;
diff --git a/bsp/juicevm/driver/drv_uart.c b/bsp/juicevm/driver/drv_uart.c
index b4fc7abab9..412a5d081a 100755
--- a/bsp/juicevm/driver/drv_uart.c
+++ b/bsp/juicevm/driver/drv_uart.c
@@ -24,7 +24,7 @@ static rt_err_t  uart_configure(struct rt_serial_device *serial, struct serial_c
 static rt_err_t  uart_control(struct rt_serial_device *serial, int cmd, void *arg);
 static int       uart_putc(struct rt_serial_device *serial, char c);
 static int       uart_getc(struct rt_serial_device *serial);
-static rt_size_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+static rt_ssize_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
 
 void UART0_DriverIRQHandler(void);
 
@@ -115,7 +115,7 @@ static int uart_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     return (0);
 }
diff --git a/bsp/k210/drivers/drv_lcd.c b/bsp/k210/drivers/drv_lcd.c
index 3e626553b7..40300b4e5d 100644
--- a/bsp/k210/drivers/drv_lcd.c
+++ b/bsp/k210/drivers/drv_lcd.c
@@ -443,7 +443,7 @@ static rt_err_t drv_lcd_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t drv_lcd_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t drv_lcd_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
 
     /* Not need */
@@ -451,7 +451,7 @@ static rt_size_t drv_lcd_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_si
     return 0;
 }
 
-static rt_size_t drv_lcd_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t drv_lcd_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
 
     /* Not need */
diff --git a/bsp/lm3s8962/drivers/sdcard.c b/bsp/lm3s8962/drivers/sdcard.c
index 55bec74635..93cce84f30 100644
--- a/bsp/lm3s8962/drivers/sdcard.c
+++ b/bsp/lm3s8962/drivers/sdcard.c
@@ -691,7 +691,7 @@ static rt_err_t rt_sdcard_close(rt_device_t dev)
 	return RT_EOK;
 }
 
-static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
 	DRESULT status;
 
@@ -705,7 +705,7 @@ static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_
 	return size;
 }
 
-static rt_size_t rt_sdcard_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
 	DRESULT status;
 
diff --git a/bsp/lm3s8962/drivers/serial.c b/bsp/lm3s8962/drivers/serial.c
index 35060f8269..9bfba0b6a1 100644
--- a/bsp/lm3s8962/drivers/serial.c
+++ b/bsp/lm3s8962/drivers/serial.c
@@ -188,7 +188,7 @@ static rt_err_t rt_serial_control(rt_device_t dev, int cmd, void *args)
 	return RT_EOK;
 }
 
-static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
 	rt_uint8_t* ptr;
 	struct rt_lm3s_serial *serial = (struct rt_lm3s_serial*)dev;
@@ -248,7 +248,7 @@ static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_
 	return (rt_size_t)ptr - (rt_size_t)buffer;
 }
 
-static rt_size_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
 	struct rt_lm3s_serial* serial;
 	char *ptr;
diff --git a/bsp/lm3s9b9x/drivers/sdcard.c b/bsp/lm3s9b9x/drivers/sdcard.c
index 55bec74635..93cce84f30 100644
--- a/bsp/lm3s9b9x/drivers/sdcard.c
+++ b/bsp/lm3s9b9x/drivers/sdcard.c
@@ -691,7 +691,7 @@ static rt_err_t rt_sdcard_close(rt_device_t dev)
 	return RT_EOK;
 }
 
-static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
 	DRESULT status;
 
@@ -705,7 +705,7 @@ static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_
 	return size;
 }
 
-static rt_size_t rt_sdcard_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
 	DRESULT status;
 
diff --git a/bsp/lm3s9b9x/drivers/serial.c b/bsp/lm3s9b9x/drivers/serial.c
index 35060f8269..9bfba0b6a1 100644
--- a/bsp/lm3s9b9x/drivers/serial.c
+++ b/bsp/lm3s9b9x/drivers/serial.c
@@ -188,7 +188,7 @@ static rt_err_t rt_serial_control(rt_device_t dev, int cmd, void *args)
 	return RT_EOK;
 }
 
-static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
 	rt_uint8_t* ptr;
 	struct rt_lm3s_serial *serial = (struct rt_lm3s_serial*)dev;
@@ -248,7 +248,7 @@ static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_
 	return (rt_size_t)ptr - (rt_size_t)buffer;
 }
 
-static rt_size_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
 	struct rt_lm3s_serial* serial;
 	char *ptr;
diff --git a/bsp/lm4f232/drivers/serial.c b/bsp/lm4f232/drivers/serial.c
index 35060f8269..9bfba0b6a1 100644
--- a/bsp/lm4f232/drivers/serial.c
+++ b/bsp/lm4f232/drivers/serial.c
@@ -188,7 +188,7 @@ static rt_err_t rt_serial_control(rt_device_t dev, int cmd, void *args)
 	return RT_EOK;
 }
 
-static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
 	rt_uint8_t* ptr;
 	struct rt_lm3s_serial *serial = (struct rt_lm3s_serial*)dev;
@@ -248,7 +248,7 @@ static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_
 	return (rt_size_t)ptr - (rt_size_t)buffer;
 }
 
-static rt_size_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
 	struct rt_lm3s_serial* serial;
 	char *ptr;
diff --git a/bsp/loongson/ls1cdev/drivers/drv_rtc.c b/bsp/loongson/ls1cdev/drivers/drv_rtc.c
index 89d72a5bb3..3f2f3af1b6 100644
--- a/bsp/loongson/ls1cdev/drivers/drv_rtc.c
+++ b/bsp/loongson/ls1cdev/drivers/drv_rtc.c
@@ -84,7 +84,7 @@ static rt_err_t rt_rtc_open(rt_device_t dev, rt_uint16_t oflag)
     return RT_EOK;
 }
 
-static rt_size_t rt_rtc_read(
+static rt_ssize_t rt_rtc_read(
     rt_device_t     dev,
     rt_off_t        pos,
     void*           buffer,
diff --git a/bsp/loongson/ls1cdev/drivers/net/synopGMAC.c b/bsp/loongson/ls1cdev/drivers/net/synopGMAC.c
index dcdf4afb03..48c043fcee 100644
--- a/bsp/loongson/ls1cdev/drivers/net/synopGMAC.c
+++ b/bsp/loongson/ls1cdev/drivers/net/synopGMAC.c
@@ -403,13 +403,13 @@ static rt_err_t eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/loongson/ls2kdev/drivers/ata/dwc_ahsata.c b/bsp/loongson/ls2kdev/drivers/ata/dwc_ahsata.c
index bf76636e06..aca793c1a1 100644
--- a/bsp/loongson/ls2kdev/drivers/ata/dwc_ahsata.c
+++ b/bsp/loongson/ls2kdev/drivers/ata/dwc_ahsata.c
@@ -1197,13 +1197,13 @@ int dwc_ahsata_probe(struct rt_device *dev)
     return dwc_ahci_start_ports(uc_priv);
 }
 
-rt_size_t dwc_ahsata_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+rt_ssize_t dwc_ahsata_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     struct blk_device *blk = (struct blk_device *)dev;
     return sata_read_common(blk->ahci_device, blk, pos, size, buffer);
 }
 
-rt_size_t dwc_ahsata_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+rt_ssize_t dwc_ahsata_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     struct blk_device *blk = (struct blk_device *)dev;
     return sata_write_common(blk->ahci_device, blk, pos, size, buffer);
diff --git a/bsp/loongson/ls2kdev/drivers/ata/dwc_ahsata.h b/bsp/loongson/ls2kdev/drivers/ata/dwc_ahsata.h
index 44e993d03e..80389a5fd6 100644
--- a/bsp/loongson/ls2kdev/drivers/ata/dwc_ahsata.h
+++ b/bsp/loongson/ls2kdev/drivers/ata/dwc_ahsata.h
@@ -18,8 +18,8 @@ int dwc_ahsata_bus_reset(struct rt_device *dev);
 int dwc_ahsata_probe(struct rt_device *dev);
 int dwc_ahsata_scan(struct rt_device *dev);
 int dwc_ahsata_port_status(struct rt_device *dev, int port);
-rt_size_t dwc_ahsata_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-rt_size_t dwc_ahsata_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+rt_ssize_t dwc_ahsata_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+rt_ssize_t dwc_ahsata_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 rt_err_t dwc_ahsata_control(rt_device_t dev, int cmd, void *args);
 
 #endif
diff --git a/bsp/loongson/ls2kdev/drivers/drv_rtc.c b/bsp/loongson/ls2kdev/drivers/drv_rtc.c
index 82cb25ddd5..ae90e2c79e 100644
--- a/bsp/loongson/ls2kdev/drivers/drv_rtc.c
+++ b/bsp/loongson/ls2kdev/drivers/drv_rtc.c
@@ -108,7 +108,7 @@ static rt_err_t rt_rtc_open(rt_device_t dev, rt_uint16_t oflag)
     return RT_EOK;
 }
 
-static rt_size_t rt_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     return 0;
 }
diff --git a/bsp/loongson/ls2kdev/drivers/net/synopGMAC.c b/bsp/loongson/ls2kdev/drivers/net/synopGMAC.c
index 22e51de712..e2c4d2bf82 100644
--- a/bsp/loongson/ls2kdev/drivers/net/synopGMAC.c
+++ b/bsp/loongson/ls2kdev/drivers/net/synopGMAC.c
@@ -423,13 +423,13 @@ static rt_err_t eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/lpc176x/drivers/emac.c b/bsp/lpc176x/drivers/emac.c
index e4f0363626..c5b11f48c7 100644
--- a/bsp/lpc176x/drivers/emac.c
+++ b/bsp/lpc176x/drivers/emac.c
@@ -342,16 +342,14 @@ static rt_err_t lpc17xx_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t lpc17xx_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t lpc17xx_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-    return 0;
+    return -RT_ENOSYS;
 }
 
-static rt_size_t lpc17xx_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t lpc17xx_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-    return 0;
+    return -RT_ENOSYS;
 }
 
 static rt_err_t lpc17xx_emac_control(rt_device_t dev, int cmd, void *args)
diff --git a/bsp/lpc176x/drivers/sd.c b/bsp/lpc176x/drivers/sd.c
index 53b57676de..27e6382825 100644
--- a/bsp/lpc176x/drivers/sd.c
+++ b/bsp/lpc176x/drivers/sd.c
@@ -438,7 +438,7 @@ static rt_err_t rt_sdcard_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     bool status;
 
@@ -450,7 +450,7 @@ static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_
     return 0;
 }
 
-static rt_size_t rt_sdcard_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     bool status;
 
diff --git a/bsp/lpc176x/drivers/uart.c b/bsp/lpc176x/drivers/uart.c
index a32952124b..82d4a4fa1d 100644
--- a/bsp/lpc176x/drivers/uart.c
+++ b/bsp/lpc176x/drivers/uart.c
@@ -203,7 +203,7 @@ static rt_err_t rt_uart_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_uart_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_uint8_t *ptr;
     struct rt_uart_lpc *uart = (struct rt_uart_lpc *)dev;
@@ -250,7 +250,7 @@ static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_si
     return 0;
 }
 
-static rt_size_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     char *ptr;
     ptr = (char *)buffer;
diff --git a/bsp/lpc178x/drivers/emac.c b/bsp/lpc178x/drivers/emac.c
index ec48ea8833..7314964f04 100644
--- a/bsp/lpc178x/drivers/emac.c
+++ b/bsp/lpc178x/drivers/emac.c
@@ -366,16 +366,14 @@ static rt_err_t lpc17xx_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t lpc17xx_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t lpc17xx_emac_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-    return 0;
+    return -RT_ENOSYS;
 }
 
-static rt_size_t lpc17xx_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t lpc17xx_emac_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-    return 0;
+    return -RT_ENOSYS;
 }
 
 static rt_err_t lpc17xx_emac_control(rt_device_t dev, int cmd, void *args)
diff --git a/bsp/lpc178x/drivers/uart.c b/bsp/lpc178x/drivers/uart.c
index cb8e68d30c..b55f487429 100644
--- a/bsp/lpc178x/drivers/uart.c
+++ b/bsp/lpc178x/drivers/uart.c
@@ -220,7 +220,7 @@ static rt_err_t rt_uart_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     struct rt_uart_lpc *uart = (struct rt_uart_lpc*)dev;
@@ -267,7 +267,7 @@ static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_si
     return 0;
 }
 
-static rt_size_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     struct rt_uart_lpc *uart = (struct rt_uart_lpc*)dev;
     char *ptr;
diff --git a/bsp/lpc2148/drivers/dm9000.c b/bsp/lpc2148/drivers/dm9000.c
index 9bc8d445f9..6677b1bf0d 100644
--- a/bsp/lpc2148/drivers/dm9000.c
+++ b/bsp/lpc2148/drivers/dm9000.c
@@ -60,13 +60,13 @@ static rt_err_t rt_dm9000_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_dm9000_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_dm9000_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_dm9000_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_dm9000_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/lpc2148/drivers/sd.c b/bsp/lpc2148/drivers/sd.c
index 144c9f2ff5..a283a4b146 100644
--- a/bsp/lpc2148/drivers/sd.c
+++ b/bsp/lpc2148/drivers/sd.c
@@ -30,7 +30,7 @@ static rt_err_t rt_sdcard_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     /* append partition offset */
     pos += part.offset * 512;
@@ -38,7 +38,7 @@ static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_
     return 0;
 }
 
-static rt_size_t rt_sdcard_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     /* append partition offset */
     pos += part.offset * 512;
diff --git a/bsp/lpc2148/drivers/serial.c b/bsp/lpc2148/drivers/serial.c
index 4fff9c78c8..284b9accae 100644
--- a/bsp/lpc2148/drivers/serial.c
+++ b/bsp/lpc2148/drivers/serial.c
@@ -190,7 +190,7 @@ static rt_err_t rt_serial_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     struct rt_lpcserial *lpc_serial = (struct rt_lpcserial*)dev;
@@ -252,7 +252,7 @@ static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_
     return (rt_size_t)ptr - (rt_size_t)buffer;
 }
 
-static rt_size_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     struct rt_lpcserial* lpc_serial;
     char *ptr;
diff --git a/bsp/lpc2478/drivers/serial.c b/bsp/lpc2478/drivers/serial.c
index e53b5075dc..d5ee6763ad 100644
--- a/bsp/lpc2478/drivers/serial.c
+++ b/bsp/lpc2478/drivers/serial.c
@@ -163,7 +163,7 @@ static rt_err_t rt_serial_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     struct rt_lpcserial *lpc_serial = (struct rt_lpcserial*)dev;
@@ -225,7 +225,7 @@ static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_
     return (rt_size_t)ptr - (rt_size_t)buffer;
 }
 
-static rt_size_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     struct rt_lpcserial* lpc_serial;
     char *ptr;
diff --git a/bsp/lpc408x/drivers/drv_emac.c b/bsp/lpc408x/drivers/drv_emac.c
index 0bae0f1456..a92aba8845 100644
--- a/bsp/lpc408x/drivers/drv_emac.c
+++ b/bsp/lpc408x/drivers/drv_emac.c
@@ -334,13 +334,13 @@ static rt_err_t lpc_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t lpc_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t lpc_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t lpc_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t lpc_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/lpc408x/drivers/drv_led.c b/bsp/lpc408x/drivers/drv_led.c
index 29c74af1af..5c18ef67d1 100644
--- a/bsp/lpc408x/drivers/drv_led.c
+++ b/bsp/lpc408x/drivers/drv_led.c
@@ -61,7 +61,7 @@ static rt_err_t rt_led_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
+static rt_ssize_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
                              rt_size_t size)
 {
     rt_ubase_t index = 0;
@@ -86,7 +86,7 @@ static rt_size_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
     return index;
 }
 
-static rt_size_t rt_led_write(rt_device_t dev, rt_off_t pos,
+static rt_ssize_t rt_led_write(rt_device_t dev, rt_off_t pos,
                               const void *buffer, rt_size_t size)
 {
     rt_ubase_t index = 0;
diff --git a/bsp/lpc43xx/drivers/drv_emac.c b/bsp/lpc43xx/drivers/drv_emac.c
index 03c6321dbf..f88505fa88 100644
--- a/bsp/lpc43xx/drivers/drv_emac.c
+++ b/bsp/lpc43xx/drivers/drv_emac.c
@@ -355,13 +355,13 @@ static rt_err_t lpc_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t lpc_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t lpc_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t lpc_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t lpc_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/lpc43xx/drivers/drv_led.c b/bsp/lpc43xx/drivers/drv_led.c
index 464ddb4f9f..02ce94d548 100644
--- a/bsp/lpc43xx/drivers/drv_led.c
+++ b/bsp/lpc43xx/drivers/drv_led.c
@@ -76,7 +76,7 @@ static rt_err_t rt_led_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
+static rt_ssize_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
                              rt_size_t size)
 {
     rt_ubase_t index = 0;
@@ -101,7 +101,7 @@ static rt_size_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
     return index;
 }
 
-static rt_size_t rt_led_write(rt_device_t dev, rt_off_t pos,
+static rt_ssize_t rt_led_write(rt_device_t dev, rt_off_t pos,
                               const void *buffer, rt_size_t size)
 {
     rt_ubase_t index = 0;
diff --git a/bsp/lpc5410x/drivers/drv_led.c b/bsp/lpc5410x/drivers/drv_led.c
index 108707aee1..fc6ca6abed 100644
--- a/bsp/lpc5410x/drivers/drv_led.c
+++ b/bsp/lpc5410x/drivers/drv_led.c
@@ -61,7 +61,7 @@ static rt_err_t rt_led_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
+static rt_ssize_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
                              rt_size_t size)
 {
     rt_ubase_t index = 0;
@@ -86,7 +86,7 @@ static rt_size_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
     return index;
 }
 
-static rt_size_t rt_led_write(rt_device_t dev, rt_off_t pos,
+static rt_ssize_t rt_led_write(rt_device_t dev, rt_off_t pos,
                               const void *buffer, rt_size_t size)
 {
     rt_ubase_t index = 0;
diff --git a/bsp/lpc54114-lite/drivers/audio/drv_sound.c b/bsp/lpc54114-lite/drivers/audio/drv_sound.c
index 409403facb..4e49a619ad 100644
--- a/bsp/lpc54114-lite/drivers/audio/drv_sound.c
+++ b/bsp/lpc54114-lite/drivers/audio/drv_sound.c
@@ -297,7 +297,7 @@ static rt_err_t lpc_audio_configure(struct rt_audio_device *audio, struct rt_aud
     return result;
 }
 
-static rt_size_t lpc_audio_transmit(struct rt_audio_device *audio, const void *writeBuf, void *readBuf, rt_size_t size)
+static rt_ssize_t lpc_audio_transmit(struct rt_audio_device *audio, const void *writeBuf, void *readBuf, rt_size_t size)
 {
     RT_ASSERT(audio != RT_NULL);
     i2s_transfer_t transfer;
diff --git a/bsp/lpc54114-lite/drivers/drv_i2c.c b/bsp/lpc54114-lite/drivers/drv_i2c.c
index cba87c8aec..4d66217898 100644
--- a/bsp/lpc54114-lite/drivers/drv_i2c.c
+++ b/bsp/lpc54114-lite/drivers/drv_i2c.c
@@ -33,7 +33,7 @@ static uint32_t get_i2c_freq(I2C_Type *base)
     return freq;
 }
 
-static rt_size_t master_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t master_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     rt_size_t ret = (0);
 
@@ -82,7 +82,7 @@ static rt_size_t master_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg ms
     return ret;
 }
 
-static rt_size_t slave_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t slave_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     return 0;
 }
diff --git a/bsp/lpc54608-LPCXpresso/drivers/drv_emac.c b/bsp/lpc54608-LPCXpresso/drivers/drv_emac.c
index 394ad22cca..6556d24125 100644
--- a/bsp/lpc54608-LPCXpresso/drivers/drv_emac.c
+++ b/bsp/lpc54608-LPCXpresso/drivers/drv_emac.c
@@ -383,13 +383,13 @@ static rt_err_t lpc_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t lpc_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t lpc_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t lpc_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t lpc_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/lpc54608-LPCXpresso/drivers/drv_i2c.c b/bsp/lpc54608-LPCXpresso/drivers/drv_i2c.c
index 1a6b5ff3b8..75807e2b96 100644
--- a/bsp/lpc54608-LPCXpresso/drivers/drv_i2c.c
+++ b/bsp/lpc54608-LPCXpresso/drivers/drv_i2c.c
@@ -143,7 +143,7 @@ struct lpc_i2c_bus
     I2C_Type *I2C;
 };
 
-static rt_size_t lpc_i2c_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t lpc_i2c_xfer(struct rt_i2c_bus_device *bus,
                               struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
diff --git a/bsp/lpc54608-LPCXpresso/drivers/drv_sd.c b/bsp/lpc54608-LPCXpresso/drivers/drv_sd.c
index 879e0d1c9c..5b288e616c 100644
--- a/bsp/lpc54608-LPCXpresso/drivers/drv_sd.c
+++ b/bsp/lpc54608-LPCXpresso/drivers/drv_sd.c
@@ -34,7 +34,7 @@ static rt_err_t rt_mci_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_mci_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_mci_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_uint8_t status = kStatus_Success;
     struct mci_device *mci = (struct mci_device *)dev;
@@ -67,7 +67,7 @@ static rt_size_t rt_mci_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_siz
     return 0;
 }
 
-static rt_size_t rt_mci_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_mci_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_uint8_t status = kStatus_Success;
     struct mci_device *mci = (struct mci_device *)dev;
diff --git a/bsp/lpc55sxx/Libraries/drivers/drv_i2c.c b/bsp/lpc55sxx/Libraries/drivers/drv_i2c.c
index 522b4b712f..bf83c41143 100644
--- a/bsp/lpc55sxx/Libraries/drivers/drv_i2c.c
+++ b/bsp/lpc55sxx/Libraries/drivers/drv_i2c.c
@@ -66,7 +66,7 @@ static void i2c_mst_dma_callback(I2C_Type *base, i2c_master_dma_handle_t *handle
     rt_sem_release(lpc_i2c->sem);
 }
 
-static rt_size_t lpc_i2c_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t lpc_i2c_xfer(struct rt_i2c_bus_device *bus,
                               struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
diff --git a/bsp/lpc55sxx/Libraries/drivers/drv_led.c b/bsp/lpc55sxx/Libraries/drivers/drv_led.c
index 8e3e59eeea..9410d5fa00 100644
--- a/bsp/lpc55sxx/Libraries/drivers/drv_led.c
+++ b/bsp/lpc55sxx/Libraries/drivers/drv_led.c
@@ -62,7 +62,7 @@ static rt_err_t rt_led_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
+static rt_ssize_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
                              rt_size_t size)
 {
     rt_ubase_t index = 0;
@@ -87,7 +87,7 @@ static rt_size_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
     return index;
 }
 
-static rt_size_t rt_led_write(rt_device_t dev, rt_off_t pos,
+static rt_ssize_t rt_led_write(rt_device_t dev, rt_off_t pos,
                               const void *buffer, rt_size_t size)
 {
     rt_ubase_t index = 0;
diff --git a/bsp/lpc55sxx/Libraries/drivers/drv_rtc.c b/bsp/lpc55sxx/Libraries/drivers/drv_rtc.c
index 65d34bbb4e..2a627bb986 100644
--- a/bsp/lpc55sxx/Libraries/drivers/drv_rtc.c
+++ b/bsp/lpc55sxx/Libraries/drivers/drv_rtc.c
@@ -87,12 +87,12 @@ static rt_err_t lpc_rtc_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t lpc_rtc_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t lpc_rtc_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     return 0;
 }
 
-static rt_size_t lpc_rtc_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t lpc_rtc_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     return 0;
 }
diff --git a/bsp/lpc824/drivers/usart.c b/bsp/lpc824/drivers/usart.c
index 54a56501c9..6aa912c081 100644
--- a/bsp/lpc824/drivers/usart.c
+++ b/bsp/lpc824/drivers/usart.c
@@ -183,7 +183,7 @@ static rt_err_t rt_uart_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     /* interrupt receive */
     rt_base_t level;
@@ -205,7 +205,7 @@ static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_si
     return length;
 }
 
-static rt_size_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     char *ptr = (char*) buffer;
     struct lpc8xx_uart* uart;
diff --git a/bsp/m16c62p/drivers/uart.c b/bsp/m16c62p/drivers/uart.c
index 67f56b98a3..c543b023ad 100644
--- a/bsp/m16c62p/drivers/uart.c
+++ b/bsp/m16c62p/drivers/uart.c
@@ -164,7 +164,7 @@ static rt_err_t rt_uart_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t *ptr;
     struct rt_uart_m16c *uart = (struct rt_uart_m16c *)dev;
@@ -211,7 +211,7 @@ static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_si
     return 0;
 }
 
-static rt_size_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     char *ptr;
     ptr = (char *)buffer;
diff --git a/bsp/maxim/libraries/HAL_Drivers/drv_i2c.c b/bsp/maxim/libraries/HAL_Drivers/drv_i2c.c
index ddacdf0a12..4ae3a06319 100644
--- a/bsp/maxim/libraries/HAL_Drivers/drv_i2c.c
+++ b/bsp/maxim/libraries/HAL_Drivers/drv_i2c.c
@@ -66,7 +66,7 @@ static struct mxc_i2c_config i2c_config[] =
 static struct mxc_i2c i2c_obj[sizeof(i2c_config) / sizeof(i2c_config[0])] = {0};
 
 
-static rt_size_t mxc_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t mxc_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                   struct rt_i2c_msg msgs[],
                                   rt_uint32_t num)
 {
diff --git a/bsp/microchip/common/board/sam_gmac.c b/bsp/microchip/common/board/sam_gmac.c
index 953c3430f4..b8f8d7a91c 100644
--- a/bsp/microchip/common/board/sam_gmac.c
+++ b/bsp/microchip/common/board/sam_gmac.c
@@ -111,14 +111,14 @@ static rt_err_t rt_sam_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_sam_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_sam_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     LOG_D("gmac read");
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_sam_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_sam_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     LOG_D("gmac write");
     rt_set_errno(-RT_ENOSYS);
diff --git a/bsp/microchip/common/board/sam_i2c.c b/bsp/microchip/common/board/sam_i2c.c
index 7196e0c87d..ea23058487 100644
--- a/bsp/microchip/common/board/sam_i2c.c
+++ b/bsp/microchip/common/board/sam_i2c.c
@@ -30,10 +30,10 @@ static struct sam_i2c_bus sam_i2c0 =
     .device_name = I2CBUS_NAME,
 };
 
-static rt_size_t sam_i2c_master_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t sam_i2c_master_xfer(struct rt_i2c_bus_device *bus,
                                      struct rt_i2c_msg msgs[],
                                      rt_uint32_t num);
-static rt_size_t sam_i2c_slave_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t sam_i2c_slave_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num);
 static rt_err_t sam_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -62,7 +62,7 @@ static inline void sam_i2c_update_control(struct rt_i2c_msg *src,
         dest->flags |= I2C_M_SEVEN;
 }
 
-static rt_size_t sam_i2c_master_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t sam_i2c_master_xfer(struct rt_i2c_bus_device *bus,
                                      struct rt_i2c_msg msgs[],
                                      rt_uint32_t num)
 {
@@ -82,7 +82,7 @@ static rt_size_t sam_i2c_master_xfer(struct rt_i2c_bus_device *bus,
     return i;
 }
 
-static rt_size_t sam_i2c_slave_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t sam_i2c_slave_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num)
 {
diff --git a/bsp/mini2440/drivers/dm9000.c b/bsp/mini2440/drivers/dm9000.c
index 2bdbd43a12..c3acda2c67 100644
--- a/bsp/mini2440/drivers/dm9000.c
+++ b/bsp/mini2440/drivers/dm9000.c
@@ -335,13 +335,13 @@ static rt_err_t rt_dm9000_close(rt_device_t dev)
 	return RT_EOK;
 }
 
-static rt_size_t rt_dm9000_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_dm9000_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
 	rt_set_errno(-RT_ENOSYS);
 	return 0;
 }
 
-static rt_size_t rt_dm9000_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_dm9000_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
 	rt_set_errno(-RT_ENOSYS);
 	return 0;
diff --git a/bsp/mini2440/drivers/key.c b/bsp/mini2440/drivers/key.c
index 459ebf2b07..dd6a81d246 100644
--- a/bsp/mini2440/drivers/key.c
+++ b/bsp/mini2440/drivers/key.c
@@ -157,7 +157,7 @@ static rt_err_t rt_key_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_key_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_key_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     rt_err_t err_code;
diff --git a/bsp/mini4020/drivers/dm9161.c b/bsp/mini4020/drivers/dm9161.c
index a5100f501b..2e15c70ba5 100644
--- a/bsp/mini4020/drivers/dm9161.c
+++ b/bsp/mini4020/drivers/dm9161.c
@@ -508,18 +508,14 @@ static rt_err_t rt_dm9161_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_dm9161_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_dm9161_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-
-    return 0;
+    return -RT_ENOSYS;
 }
 
-static rt_size_t rt_dm9161_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_dm9161_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
-    rt_set_errno(-RT_ENOSYS);
-
-    return 0;
+    return -RT_ENOSYS;
 }
 
 static rt_err_t rt_dm9161_control(rt_device_t dev, int cmd, void *args)
diff --git a/bsp/mini4020/drivers/sdcard.c b/bsp/mini4020/drivers/sdcard.c
index bf2192382f..4e497ed5f0 100644
--- a/bsp/mini4020/drivers/sdcard.c
+++ b/bsp/mini4020/drivers/sdcard.c
@@ -524,7 +524,7 @@ static rt_err_t rt_sdcard_control(rt_device_t dev, int cmd, void *args)
  *
  * @param hook the hook function
  */
-static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_uint32_t retry = 3;
     rt_uint8_t  status;
@@ -582,7 +582,7 @@ static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_
  *
  * @param hook the hook function
  */
-static rt_size_t rt_sdcard_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     int i;
     rt_uint8_t status;
diff --git a/bsp/n32/libraries/n32_drivers/drv_i2c.c b/bsp/n32/libraries/n32_drivers/drv_i2c.c
index a5c8f62050..d64f9288fd 100644
--- a/bsp/n32/libraries/n32_drivers/drv_i2c.c
+++ b/bsp/n32/libraries/n32_drivers/drv_i2c.c
@@ -336,7 +336,7 @@ static int rt_i2c_write(rt_uint32_t i2c_periph, uint16_t slave_address, uint8_t*
 
 
 
-static rt_size_t rt_i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t rt_i2c_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
     rt_uint32_t i;
diff --git a/bsp/nios_ii/uart.c b/bsp/nios_ii/uart.c
index 79c2dcc586..abc4aed0a0 100644
--- a/bsp/nios_ii/uart.c
+++ b/bsp/nios_ii/uart.c
@@ -51,7 +51,7 @@ static rt_err_t rt_uart_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     if( rx_get_index )
     {
@@ -62,7 +62,7 @@ static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_si
     return 0;
 }
 
-static rt_size_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     const char * write_point = buffer;
     while(size--)
diff --git a/bsp/nrf5x/libraries/drivers/drv_i2c.c b/bsp/nrf5x/libraries/drivers/drv_i2c.c
index e86c86507d..d66b74a83f 100644
--- a/bsp/nrf5x/libraries/drivers/drv_i2c.c
+++ b/bsp/nrf5x/libraries/drivers/drv_i2c.c
@@ -89,7 +89,7 @@ static int twi_master_init(struct rt_i2c_bus_device *bus)
     return 0;
 }
 
-static rt_size_t _master_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t _master_xfer(struct rt_i2c_bus_device *bus,
                               struct rt_i2c_msg msgs[],
                               rt_uint32_t num)
 {
diff --git a/bsp/nuclei/libraries/gd32vf103/HAL_Drivers/drv_i2c.c b/bsp/nuclei/libraries/gd32vf103/HAL_Drivers/drv_i2c.c
index 94aa0e234c..f7d3f85192 100644
--- a/bsp/nuclei/libraries/gd32vf103/HAL_Drivers/drv_i2c.c
+++ b/bsp/nuclei/libraries/gd32vf103/HAL_Drivers/drv_i2c.c
@@ -119,7 +119,7 @@ static void gd32_i2c_configure(struct gd32_i2c_config *i2c_cfg)
 }
 
 
-static rt_size_t gd32_i2c_xfer(struct rt_i2c_bus_device *device, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t gd32_i2c_xfer(struct rt_i2c_bus_device *device, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
     rt_uint32_t i;
diff --git a/bsp/nuclei/libraries/gd32vf103/HAL_Drivers/drv_rtc.c b/bsp/nuclei/libraries/gd32vf103/HAL_Drivers/drv_rtc.c
index 1d1c5ced78..1bda274950 100644
--- a/bsp/nuclei/libraries/gd32vf103/HAL_Drivers/drv_rtc.c
+++ b/bsp/nuclei/libraries/gd32vf103/HAL_Drivers/drv_rtc.c
@@ -98,12 +98,12 @@ static rt_err_t gd32_rtc_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t gd32_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t gd32_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     return RT_EOK;
 }
 
-static rt_size_t gd32_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t gd32_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     return RT_EOK;
 }
diff --git a/bsp/nuvoton/libraries/m031/rtt_port/drv_i2c.c b/bsp/nuvoton/libraries/m031/rtt_port/drv_i2c.c
index 7487414dec..24aaddd04d 100644
--- a/bsp/nuvoton/libraries/m031/rtt_port/drv_i2c.c
+++ b/bsp/nuvoton/libraries/m031/rtt_port/drv_i2c.c
@@ -69,7 +69,7 @@ static nu_i2c_bus_t nu_i2c1 =
 /* Private functions ------------------------------------------------------------*/
 #if (defined(BSP_USING_I2C0) || defined(BSP_USING_I2C1))
 
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num);
 static rt_err_t nu_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -162,7 +162,7 @@ static rt_err_t nu_i2c_send_address(nu_i2c_bus_t *nu_i2c,
     return RT_EOK;
 }
 
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num)
 {
diff --git a/bsp/nuvoton/libraries/m031/rtt_port/drv_pdma.c b/bsp/nuvoton/libraries/m031/rtt_port/drv_pdma.c
index de6dba3bc5..492c35ba5f 100644
--- a/bsp/nuvoton/libraries/m031/rtt_port/drv_pdma.c
+++ b/bsp/nuvoton/libraries/m031/rtt_port/drv_pdma.c
@@ -66,7 +66,7 @@ static void nu_pdma_channel_disable(int i32ChannID);
 static void nu_pdma_channel_reset(int i32ChannID);
 static rt_err_t nu_pdma_timeout_set(int i32ChannID, int i32Timeout_us);
 static void nu_pdma_periph_ctrl_fill(int i32ChannID, int i32CtlPoolIdx);
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int count, nu_pdma_memctrl_t eMemCtl);
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int count, nu_pdma_memctrl_t eMemCtl);
 static void nu_pdma_memfun_cb(void *pvUserData, uint32_t u32Events);
 static void nu_pdma_memfun_actor_init(void);
 static int nu_pdma_memfun_employ(void);
@@ -910,7 +910,7 @@ static int nu_pdma_memfun_employ(void)
     return idx;
 }
 
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
 {
     nu_pdma_memfun_actor_t psMemFunActor = NULL;
     int idx;
diff --git a/bsp/nuvoton/libraries/m031/rtt_port/drv_rtc.c b/bsp/nuvoton/libraries/m031/rtt_port/drv_rtc.c
index e280b1c3b8..7005a3149f 100644
--- a/bsp/nuvoton/libraries/m031/rtt_port/drv_rtc.c
+++ b/bsp/nuvoton/libraries/m031/rtt_port/drv_rtc.c
@@ -53,8 +53,8 @@
 static rt_err_t nu_rtc_control(rt_device_t dev, int cmd, void *args);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
-static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 #endif
 
 static rt_err_t nu_rtc_is_date_valid(const time_t t);
@@ -153,7 +153,7 @@ INIT_BOARD_EXPORT(rt_hw_rtc_init);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.read() entry. */
-static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_GET_TIME, buffer);
@@ -165,7 +165,7 @@ static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_siz
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.write() entry. */
-static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_SET_TIME, (void *)buffer);
diff --git a/bsp/nuvoton/libraries/m031/rtt_port/drv_spi.c b/bsp/nuvoton/libraries/m031/rtt_port/drv_spi.c
index 21f9f2fb61..6e5e38b20b 100644
--- a/bsp/nuvoton/libraries/m031/rtt_port/drv_spi.c
+++ b/bsp/nuvoton/libraries/m031/rtt_port/drv_spi.c
@@ -55,7 +55,7 @@ static rt_err_t nu_spi_bus_configure(struct rt_spi_device *device, struct rt_spi
     static void nu_pdma_spi_rx_cb(void *pvUserData, uint32_t u32EventFilter);
     static rt_err_t nu_pdma_spi_rx_config(struct nu_spi *spi_bus, uint8_t *pu8Buf, int32_t i32RcvLen, uint8_t bytes_per_word);
     static rt_err_t nu_pdma_spi_tx_config(struct nu_spi *spi_bus, const uint8_t *pu8Buf, int32_t i32SndLen, uint8_t bytes_per_word);
-    static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
+    static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
 #endif
 /* Public functions -------------------------------------------------------------*/
 void nu_spi_transfer(struct nu_spi *spi_bus, uint8_t *tx, uint8_t *rx, int length, uint8_t bytes_per_word);
@@ -300,7 +300,7 @@ exit_nu_pdma_spi_tx_config:
 /**
  * SPI PDMA transfer
  */
-static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
+static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
 {
     rt_err_t result = RT_EOK;
     rt_uint32_t u32Offset = 0;
diff --git a/bsp/nuvoton/libraries/m031/rtt_port/drv_uart.c b/bsp/nuvoton/libraries/m031/rtt_port/drv_uart.c
index 58e0ffc4db..c5943fd490 100644
--- a/bsp/nuvoton/libraries/m031/rtt_port/drv_uart.c
+++ b/bsp/nuvoton/libraries/m031/rtt_port/drv_uart.c
@@ -85,7 +85,7 @@ static int nu_uart_receive(struct rt_serial_device *serial);
 static void nu_uart_isr(nu_uart_t serial);
 
 #if defined(RT_SERIAL_USING_DMA)
-    static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+    static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
     static void nu_pdma_uart_rx_cb(void *pvOwner, uint32_t u32Events);
     static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events);
 #endif
@@ -624,7 +624,7 @@ static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events)
 /**
  * Uart DMA transfer
  */
-static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     rt_err_t result = RT_EOK;
     nu_uart_t psNuUart = (nu_uart_t)serial;
diff --git a/bsp/nuvoton/libraries/m031/rtt_port/drv_ui2c.c b/bsp/nuvoton/libraries/m031/rtt_port/drv_ui2c.c
index 4f4d143784..a59446210c 100644
--- a/bsp/nuvoton/libraries/m031/rtt_port/drv_ui2c.c
+++ b/bsp/nuvoton/libraries/m031/rtt_port/drv_ui2c.c
@@ -37,7 +37,7 @@ typedef struct nu_ui2c_bus
 } nu_ui2c_bus_t;
 
 /* Private functions ------------------------------------------------------------*/
-static rt_size_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *ui2c_dev,
+static rt_ssize_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *ui2c_dev,
                                   struct rt_i2c_msg msgs[],
                                   rt_uint32_t num);
 
@@ -188,7 +188,7 @@ static rt_err_t nu_ui2c_send_address(nu_ui2c_bus_t *nu_ui2c,
     return RT_EOK;
 }
 
-static rt_size_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                   struct rt_i2c_msg msgs[],
                                   rt_uint32_t num)
 {
diff --git a/bsp/nuvoton/libraries/m031/rtt_port/drv_usbd.c b/bsp/nuvoton/libraries/m031/rtt_port/drv_usbd.c
index 9cbb7dba12..b672880c0a 100644
--- a/bsp/nuvoton/libraries/m031/rtt_port/drv_usbd.c
+++ b/bsp/nuvoton/libraries/m031/rtt_port/drv_usbd.c
@@ -191,7 +191,7 @@ static rt_err_t _ep_disable(uep_t ep)
     return RT_EOK;
 }
 
-static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
+static rt_ssize_t _ep_read(rt_uint8_t address, void *buffer)
 {
     rt_size_t size = 0;
     rt_uint8_t *buf;
@@ -207,7 +207,7 @@ static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
     return size;
 }
 
-static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT(!(address & USB_DIR_IN));
 
@@ -216,7 +216,7 @@ static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t si
     return size;
 }
 
-static rt_size_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT((address & USB_DIR_IN));
 
diff --git a/bsp/nuvoton/libraries/m031/rtt_port/drv_uspi.c b/bsp/nuvoton/libraries/m031/rtt_port/drv_uspi.c
index a3296a9163..a402013754 100644
--- a/bsp/nuvoton/libraries/m031/rtt_port/drv_uspi.c
+++ b/bsp/nuvoton/libraries/m031/rtt_port/drv_uspi.c
@@ -78,7 +78,7 @@ static void nu_uspi_drain_rxfifo(USPI_T *uspi_base);
     static void nu_pdma_uspi_rx_cb(void *pvUserData, uint32_t u32EventFilter);
     static rt_err_t nu_pdma_uspi_rx_config(struct nu_uspi *uspi_bus, uint8_t *pu8Buf, int32_t i32RcvLen, uint8_t bytes_per_word);
     static rt_err_t nu_pdma_uspi_tx_config(struct nu_uspi *uspi_bus, const uint8_t *pu8Buf, int32_t i32SndLen, uint8_t bytes_per_word);
-    static rt_size_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
+    static rt_ssize_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
     static rt_err_t nu_hw_uspi_pdma_allocate(struct nu_uspi *uspi_bus);
 #endif
 /* Public functions -------------------------------------------------------------*/
@@ -341,7 +341,7 @@ exit_nu_pdma_uspi_tx_config:
 /**
  * USPI PDMA transfer
  **/
-static rt_size_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
+static rt_ssize_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
 {
     rt_err_t result = RT_EOK;
     rt_uint32_t u32Offset = 0;
diff --git a/bsp/nuvoton/libraries/m031/rtt_port/drv_uuart.c b/bsp/nuvoton/libraries/m031/rtt_port/drv_uuart.c
index 49f4750a5f..6277c8054d 100644
--- a/bsp/nuvoton/libraries/m031/rtt_port/drv_uuart.c
+++ b/bsp/nuvoton/libraries/m031/rtt_port/drv_uuart.c
@@ -64,7 +64,7 @@ static int nu_uuart_receive(struct rt_serial_device *serial);
 static void nu_uuart_isr(nu_uuart_t serial);
 
 #if defined(RT_SERIAL_USING_DMA)
-    static rt_size_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+    static rt_ssize_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
     static void nu_pdma_uuart_rx_cb(void *pvOwner, uint32_t u32Events);
     static void nu_pdma_uuart_tx_cb(void *pvOwner, uint32_t u32Events);
 #endif
@@ -406,7 +406,7 @@ static void nu_pdma_uuart_tx_cb(void *pvOwner, uint32_t u32Events)
 /**
  * UUart DMA transfer
  */
-static rt_size_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     rt_err_t result = RT_EOK;
 
diff --git a/bsp/nuvoton/libraries/m2354/rtt_port/drv_i2c.c b/bsp/nuvoton/libraries/m2354/rtt_port/drv_i2c.c
index 30bffc49bf..d9faf7f137 100644
--- a/bsp/nuvoton/libraries/m2354/rtt_port/drv_i2c.c
+++ b/bsp/nuvoton/libraries/m2354/rtt_port/drv_i2c.c
@@ -78,7 +78,7 @@ static nu_i2c_bus_t nu_i2c2 =
 /* Private functions ------------------------------------------------------------*/
 #if (defined(BSP_USING_I2C0) || defined(BSP_USING_I2C1) || defined(BSP_USING_I2C2))
 
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num);
 static rt_err_t nu_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -226,7 +226,7 @@ static rt_err_t nu_i2c_send_address(nu_i2c_bus_t *nu_i2c,
     return RT_EOK;
 }
 
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num)
 {
diff --git a/bsp/nuvoton/libraries/m2354/rtt_port/drv_pdma.c b/bsp/nuvoton/libraries/m2354/rtt_port/drv_pdma.c
index 5028c1a267..35398a42ab 100644
--- a/bsp/nuvoton/libraries/m2354/rtt_port/drv_pdma.c
+++ b/bsp/nuvoton/libraries/m2354/rtt_port/drv_pdma.c
@@ -69,7 +69,7 @@ static void nu_pdma_channel_disable(int i32ChannID);
 static void nu_pdma_channel_reset(int i32ChannID);
 static rt_err_t nu_pdma_timeout_set(int i32ChannID, int i32Timeout_us);
 static void nu_pdma_periph_ctrl_fill(int i32ChannID, int i32CtlPoolIdx);
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int count, nu_pdma_memctrl_t eMemCtl);
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int count, nu_pdma_memctrl_t eMemCtl);
 static void nu_pdma_memfun_cb(void *pvUserData, uint32_t u32Events);
 static void nu_pdma_memfun_actor_init(void);
 static int nu_pdma_memfun_employ(void);
@@ -948,7 +948,7 @@ static int nu_pdma_memfun_employ(void)
     return idx;
 }
 
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
 {
     nu_pdma_memfun_actor_t psMemFunActor = NULL;
     int idx;
diff --git a/bsp/nuvoton/libraries/m2354/rtt_port/drv_rtc.c b/bsp/nuvoton/libraries/m2354/rtt_port/drv_rtc.c
index e2badc01b4..1e279f538e 100644
--- a/bsp/nuvoton/libraries/m2354/rtt_port/drv_rtc.c
+++ b/bsp/nuvoton/libraries/m2354/rtt_port/drv_rtc.c
@@ -53,8 +53,8 @@
 static rt_err_t nu_rtc_control(rt_device_t dev, int cmd, void *args);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
-    static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-    static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 #endif
 
 static rt_err_t nu_rtc_is_date_valid(const time_t t);
@@ -156,7 +156,7 @@ INIT_BOARD_EXPORT(rt_hw_rtc_init);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.read() entry. */
-static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_GET_TIME, buffer);
@@ -168,7 +168,7 @@ static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_siz
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.write() entry. */
-static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_SET_TIME, (void *)buffer);
diff --git a/bsp/nuvoton/libraries/m2354/rtt_port/drv_sdh.c b/bsp/nuvoton/libraries/m2354/rtt_port/drv_sdh.c
index 62b599c6af..fa1b36b09d 100644
--- a/bsp/nuvoton/libraries/m2354/rtt_port/drv_sdh.c
+++ b/bsp/nuvoton/libraries/m2354/rtt_port/drv_sdh.c
@@ -105,7 +105,7 @@ static void nu_sdh_isr(nu_sdh_t sdh);
 static rt_err_t nu_sdh_init(rt_device_t dev);
 static rt_err_t nu_sdh_open(rt_device_t dev, rt_uint16_t oflag);
 static rt_err_t nu_sdh_close(rt_device_t dev);
-static rt_size_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb);
+static rt_ssize_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb);
 static rt_err_t nu_sdh_control(rt_device_t dev, int cmd, void *args);
 static int rt_hw_sdh_init(void);
 
@@ -234,7 +234,7 @@ static rt_err_t nu_sdh_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb)
+static rt_ssize_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb)
 {
     rt_uint32_t ret = 0;
     nu_sdh_t sdh = (nu_sdh_t)dev;
@@ -296,7 +296,7 @@ exit_nu_sdh_read:
     return 0;
 }
 
-static rt_size_t nu_sdh_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t blk_nb)
+static rt_ssize_t nu_sdh_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t blk_nb)
 {
     rt_uint32_t ret = 0;
     nu_sdh_t sdh = (nu_sdh_t)dev;
diff --git a/bsp/nuvoton/libraries/m2354/rtt_port/drv_slcd.c b/bsp/nuvoton/libraries/m2354/rtt_port/drv_slcd.c
index d9c17295b0..c298c2c9a6 100644
--- a/bsp/nuvoton/libraries/m2354/rtt_port/drv_slcd.c
+++ b/bsp/nuvoton/libraries/m2354/rtt_port/drv_slcd.c
@@ -102,7 +102,7 @@ static rt_err_t nu_slcd_close(struct rt_device *dev)
     return RT_EOK;
 }
 
-static rt_size_t nu_slcd_write(struct rt_device *dev,
+static rt_ssize_t nu_slcd_write(struct rt_device *dev,
                                rt_off_t          pos,
                                const void       *buffer,
                                rt_size_t         size)
diff --git a/bsp/nuvoton/libraries/m2354/rtt_port/drv_spi.c b/bsp/nuvoton/libraries/m2354/rtt_port/drv_spi.c
index fcbbf62935..2353effc5d 100644
--- a/bsp/nuvoton/libraries/m2354/rtt_port/drv_spi.c
+++ b/bsp/nuvoton/libraries/m2354/rtt_port/drv_spi.c
@@ -64,7 +64,7 @@ static rt_err_t nu_spi_bus_configure(struct rt_spi_device *device, struct rt_spi
     static void nu_pdma_spi_rx_cb(void *pvUserData, uint32_t u32EventFilter);
     static rt_err_t nu_pdma_spi_rx_config(struct nu_spi *spi_bus, uint8_t *pu8Buf, int32_t i32RcvLen, uint8_t bytes_per_word);
     static rt_err_t nu_pdma_spi_tx_config(struct nu_spi *spi_bus, const uint8_t *pu8Buf, int32_t i32SndLen, uint8_t bytes_per_word);
-    static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
+    static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
 #endif
 /* Public functions -------------------------------------------------------------*/
 void nu_spi_transfer(struct nu_spi *spi_bus, uint8_t *tx, uint8_t *rx, int length, uint8_t bytes_per_word);
@@ -360,7 +360,7 @@ exit_nu_pdma_spi_tx_config:
 /**
  * SPI PDMA transfer
  */
-static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
+static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
 {
     rt_err_t result = RT_EOK;
     rt_uint32_t u32Offset = 0;
diff --git a/bsp/nuvoton/libraries/m2354/rtt_port/drv_uart.c b/bsp/nuvoton/libraries/m2354/rtt_port/drv_uart.c
index fa2bd491f3..6c27efb396 100644
--- a/bsp/nuvoton/libraries/m2354/rtt_port/drv_uart.c
+++ b/bsp/nuvoton/libraries/m2354/rtt_port/drv_uart.c
@@ -79,7 +79,7 @@ static int nu_uart_receive(struct rt_serial_device *serial);
 static void nu_uart_isr(nu_uart_t serial);
 
 #if defined(RT_SERIAL_USING_DMA)
-    static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+    static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
     static void nu_pdma_uart_rx_cb(void *pvOwner, uint32_t u32Events);
     static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events);
 #endif
@@ -579,7 +579,7 @@ static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events)
 /**
  * Uart DMA transfer
  */
-static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     rt_err_t result = RT_EOK;
     nu_uart_t psNuUart = (nu_uart_t)serial;
diff --git a/bsp/nuvoton/libraries/m2354/rtt_port/drv_ui2c.c b/bsp/nuvoton/libraries/m2354/rtt_port/drv_ui2c.c
index a2f2648f1a..db664bdddd 100644
--- a/bsp/nuvoton/libraries/m2354/rtt_port/drv_ui2c.c
+++ b/bsp/nuvoton/libraries/m2354/rtt_port/drv_ui2c.c
@@ -37,7 +37,7 @@ typedef struct nu_ui2c_bus
 } nu_ui2c_bus_t;
 
 /* Private functions ------------------------------------------------------------*/
-static rt_size_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *ui2c_dev,
+static rt_ssize_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *ui2c_dev,
                                   struct rt_i2c_msg msgs[],
                                   rt_uint32_t num);
 
@@ -188,7 +188,7 @@ static rt_err_t nu_ui2c_send_address(nu_ui2c_bus_t *nu_ui2c,
     return RT_EOK;
 }
 
-static rt_size_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                   struct rt_i2c_msg msgs[],
                                   rt_uint32_t num)
 {
diff --git a/bsp/nuvoton/libraries/m2354/rtt_port/drv_usbd.c b/bsp/nuvoton/libraries/m2354/rtt_port/drv_usbd.c
index ce601c4253..bd4fb0092a 100644
--- a/bsp/nuvoton/libraries/m2354/rtt_port/drv_usbd.c
+++ b/bsp/nuvoton/libraries/m2354/rtt_port/drv_usbd.c
@@ -229,7 +229,7 @@ static rt_err_t _ep_disable(uep_t ep)
     return RT_EOK;
 }
 
-static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
+static rt_ssize_t _ep_read(rt_uint8_t address, void *buffer)
 {
     rt_size_t size = 0;
     rt_uint8_t *buf;
@@ -245,7 +245,7 @@ static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
     return size;
 }
 
-static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT(!(address & USB_DIR_IN));
 
@@ -254,7 +254,7 @@ static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t si
     return size;
 }
 
-static rt_size_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT((address & USB_DIR_IN));
 
diff --git a/bsp/nuvoton/libraries/m2354/rtt_port/drv_uspi.c b/bsp/nuvoton/libraries/m2354/rtt_port/drv_uspi.c
index a49784dde1..4b86edae22 100644
--- a/bsp/nuvoton/libraries/m2354/rtt_port/drv_uspi.c
+++ b/bsp/nuvoton/libraries/m2354/rtt_port/drv_uspi.c
@@ -78,7 +78,7 @@ static void nu_uspi_drain_rxfifo(USPI_T *uspi_base);
     static void nu_pdma_uspi_rx_cb(void *pvUserData, uint32_t u32EventFilter);
     static rt_err_t nu_pdma_uspi_rx_config(struct nu_uspi *uspi_bus, uint8_t *pu8Buf, int32_t i32RcvLen, uint8_t bytes_per_word);
     static rt_err_t nu_pdma_uspi_tx_config(struct nu_uspi *uspi_bus, const uint8_t *pu8Buf, int32_t i32SndLen, uint8_t bytes_per_word);
-    static rt_size_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
+    static rt_ssize_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
     static rt_err_t nu_hw_uspi_pdma_allocate(struct nu_uspi *uspi_bus);
 #endif
 /* Public functions -------------------------------------------------------------*/
@@ -341,7 +341,7 @@ exit_nu_pdma_uspi_tx_config:
 /**
  * USPI PDMA transfer
  **/
-static rt_size_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
+static rt_ssize_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
 {
     rt_err_t result = RT_EOK;
     rt_uint32_t u32Offset = 0;
diff --git a/bsp/nuvoton/libraries/m2354/rtt_port/drv_uuart.c b/bsp/nuvoton/libraries/m2354/rtt_port/drv_uuart.c
index 04019f3463..0317956b86 100644
--- a/bsp/nuvoton/libraries/m2354/rtt_port/drv_uuart.c
+++ b/bsp/nuvoton/libraries/m2354/rtt_port/drv_uuart.c
@@ -64,7 +64,7 @@ static int nu_uuart_receive(struct rt_serial_device *serial);
 static void nu_uuart_isr(nu_uuart_t serial);
 
 #if defined(RT_SERIAL_USING_DMA)
-    static rt_size_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+    static rt_ssize_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
     static void nu_pdma_uuart_rx_cb(void *pvOwner, uint32_t u32Events);
     static void nu_pdma_uuart_tx_cb(void *pvOwner, uint32_t u32Events);
 #endif
@@ -415,7 +415,7 @@ static void nu_pdma_uuart_tx_cb(void *pvOwner, uint32_t u32Events)
 /**
  * UUart DMA transfer
  */
-static rt_size_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     rt_err_t result = RT_EOK;
 
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/drv_hsusbd.c b/bsp/nuvoton/libraries/m460/rtt_port/drv_hsusbd.c
index a242d21690..7fe61988c6 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/drv_hsusbd.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/drv_hsusbd.c
@@ -404,7 +404,7 @@ __STATIC_INLINE void nu_buffer_cpy(rt_uint8_t address, void *buffer, rt_size_t s
     }
 }
 
-static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
+static rt_ssize_t _ep_read(rt_uint8_t address, void *buffer)
 {
     rt_size_t size  = 0;
 
@@ -432,7 +432,7 @@ static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
     return size;
 }
 
-static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT(!(address & USB_DIR_IN));
 
@@ -464,7 +464,7 @@ static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t si
     return size;
 }
 
-static rt_size_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
 {
 
     RT_ASSERT((address & USB_DIR_IN));
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/drv_i2c.c b/bsp/nuvoton/libraries/m460/rtt_port/drv_i2c.c
index 9aeda3c3f7..c051fdfba1 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/drv_i2c.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/drv_i2c.c
@@ -90,7 +90,7 @@ static struct nu_i2c_bus nu_i2c_arr [ ] =
 };
 /* Private functions ------------------------------------------------------------*/
 #if defined(BSP_USING_I2C)
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num);
 static rt_err_t nu_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -238,7 +238,7 @@ static rt_err_t nu_i2c_send_address(nu_i2c_bus_t nu_i2c,
     return RT_EOK;
 }
 
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num)
 {
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/drv_pdma.c b/bsp/nuvoton/libraries/m460/rtt_port/drv_pdma.c
index 3ee2c2f85e..f0a931a9a4 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/drv_pdma.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/drv_pdma.c
@@ -84,7 +84,7 @@ static void nu_pdma_channel_disable(int i32ChannID);
 static void nu_pdma_channel_reset(int i32ChannID);
 static rt_err_t nu_pdma_timeout_set(int i32ChannID, int i32Timeout_us);
 static void nu_pdma_periph_ctrl_fill(int i32ChannID, int i32CtlPoolIdx);
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl);
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl);
 static void nu_pdma_memfun_cb(void *pvUserData, uint32_t u32Events);
 static void nu_pdma_memfun_actor_init(void);
 static int nu_pdma_memfun_employ(void);
@@ -1174,7 +1174,7 @@ static int nu_pdma_memfun_employ(void)
     return idx;
 }
 
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
 {
     nu_pdma_memfun_actor_t psMemFunActor = NULL;
     struct nu_pdma_chn_cb sChnCB;
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/drv_rtc.c b/bsp/nuvoton/libraries/m460/rtt_port/drv_rtc.c
index 6cb129ad07..31d71a5b87 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/drv_rtc.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/drv_rtc.c
@@ -53,8 +53,8 @@
 static rt_err_t nu_rtc_control(rt_device_t dev, int cmd, void *args);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
-    static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-    static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 #endif
 
 static rt_err_t nu_rtc_is_date_valid(const time_t t);
@@ -155,7 +155,7 @@ INIT_BOARD_EXPORT(rt_hw_rtc_init);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.read() entry. */
-static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_GET_TIME, buffer);
@@ -167,7 +167,7 @@ static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_siz
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.write() entry. */
-static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_SET_TIME, (void *)buffer);
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/drv_sdh.c b/bsp/nuvoton/libraries/m460/rtt_port/drv_sdh.c
index 55a1f404e6..897784e60d 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/drv_sdh.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/drv_sdh.c
@@ -117,7 +117,7 @@ static void nu_sdh_isr(nu_sdh_t sdh);
 static rt_err_t nu_sdh_init(rt_device_t dev);
 static rt_err_t nu_sdh_open(rt_device_t dev, rt_uint16_t oflag);
 static rt_err_t nu_sdh_close(rt_device_t dev);
-static rt_size_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb);
+static rt_ssize_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb);
 static rt_err_t nu_sdh_control(rt_device_t dev, int cmd, void *args);
 static int rt_hw_sdh_init(void);
 
@@ -272,7 +272,7 @@ static rt_err_t nu_sdh_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb)
+static rt_ssize_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb)
 {
     rt_uint32_t ret = 0;
     nu_sdh_t sdh = (nu_sdh_t)dev;
@@ -334,7 +334,7 @@ exit_nu_sdh_read:
     return 0;
 }
 
-static rt_size_t nu_sdh_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t blk_nb)
+static rt_ssize_t nu_sdh_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t blk_nb)
 {
     rt_uint32_t ret = 0;
     nu_sdh_t sdh = (nu_sdh_t)dev;
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/drv_spi.c b/bsp/nuvoton/libraries/m460/rtt_port/drv_spi.c
index 8c83869dc4..940578dd34 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/drv_spi.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/drv_spi.c
@@ -85,7 +85,7 @@ static rt_err_t nu_spi_bus_configure(struct rt_spi_device *device, struct rt_spi
     static void nu_pdma_spi_rx_cb_event(void *pvUserData, uint32_t u32EventFilter);
     static rt_err_t nu_pdma_spi_rx_config(struct nu_spi *spi_bus, uint8_t *pu8Buf, int32_t i32RcvLen, uint8_t bytes_per_word);
     static rt_err_t nu_pdma_spi_tx_config(struct nu_spi *spi_bus, const uint8_t *pu8Buf, int32_t i32SndLen, uint8_t bytes_per_word);
-    static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
+    static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
 #endif
 /* Public functions -------------------------------------------------------------*/
 void nu_spi_transfer(struct nu_spi *spi_bus, uint8_t *tx, uint8_t *rx, int length, uint8_t bytes_per_word);
@@ -550,7 +550,7 @@ exit_nu_pdma_spi_tx_config:
 /**
  * SPI PDMA transfer
  */
-static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
+static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
 {
     rt_err_t result = RT_EOK;
 
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/drv_uart.c b/bsp/nuvoton/libraries/m460/rtt_port/drv_uart.c
index 426f0bf483..153e8abee6 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/drv_uart.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/drv_uart.c
@@ -87,7 +87,7 @@ static int nu_uart_receive(struct rt_serial_device *serial);
 static void nu_uart_isr(nu_uart_t serial);
 
 #if defined(RT_SERIAL_USING_DMA)
-    static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+    static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
     static void nu_pdma_uart_rx_cb(void *pvOwner, uint32_t u32Events);
     static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events);
 #endif
@@ -784,7 +784,7 @@ static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events)
 /**
  * Uart DMA transfer
  */
-static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     rt_err_t result = RT_EOK;
     nu_uart_t psNuUart = (nu_uart_t)serial;
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/drv_ui2c.c b/bsp/nuvoton/libraries/m460/rtt_port/drv_ui2c.c
index d6fab24375..85783a53d3 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/drv_ui2c.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/drv_ui2c.c
@@ -56,7 +56,7 @@ static struct nu_ui2c_bus nu_ui2c_arr [ ] =
 #endif
 };
 /* Private functions ------------------------------------------------------------*/
-static rt_size_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                   struct rt_i2c_msg msgs[],
                                   rt_uint32_t num);
 
@@ -208,7 +208,7 @@ static rt_err_t nu_ui2c_send_address(nu_ui2c_bus_t nu_ui2c,
     return RT_EOK;
 }
 
-static rt_size_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                   struct rt_i2c_msg msgs[],
                                   rt_uint32_t num)
 {
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/drv_usbd.c b/bsp/nuvoton/libraries/m460/rtt_port/drv_usbd.c
index 0011cacb22..afcd3b3fcf 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/drv_usbd.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/drv_usbd.c
@@ -276,7 +276,7 @@ static rt_err_t _ep_disable(uep_t ep)
     return RT_EOK;
 }
 
-static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
+static rt_ssize_t _ep_read(rt_uint8_t address, void *buffer)
 {
     rt_size_t size = 0;
     rt_uint8_t *buf;
@@ -292,7 +292,7 @@ static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
     return size;
 }
 
-static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT(!(address & USB_DIR_IN));
 
@@ -301,7 +301,7 @@ static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t si
     return size;
 }
 
-static rt_size_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT((address & USB_DIR_IN));
 
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/drv_uspi.c b/bsp/nuvoton/libraries/m460/rtt_port/drv_uspi.c
index 21a0402c06..36eaffeead 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/drv_uspi.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/drv_uspi.c
@@ -75,7 +75,7 @@ static void nu_uspi_drain_rxfifo(USPI_T *uspi_base);
     static void nu_pdma_uspi_rx_cb_event(void *pvUserData, uint32_t u32EventFilter);
     static rt_err_t nu_pdma_uspi_rx_config(struct nu_uspi *uspi_bus, uint8_t *pu8Buf, int32_t i32RcvLen, uint8_t bytes_per_word);
     static rt_err_t nu_pdma_uspi_tx_config(struct nu_uspi *uspi_bus, const uint8_t *pu8Buf, int32_t i32SndLen, uint8_t bytes_per_word);
-    static rt_size_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
+    static rt_ssize_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
     static rt_err_t nu_hw_uspi_pdma_allocate(struct nu_uspi *uspi_bus);
 #endif
 /* Public functions -------------------------------------------------------------*/
@@ -362,7 +362,7 @@ exit_nu_pdma_uspi_tx_config:
 /**
  * USPI PDMA transfer
  **/
-static rt_size_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
+static rt_ssize_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
 {
     rt_err_t result = RT_EOK;
 
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/drv_uuart.c b/bsp/nuvoton/libraries/m460/rtt_port/drv_uuart.c
index 16dd5b2c8b..a0a138a019 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/drv_uuart.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/drv_uuart.c
@@ -63,7 +63,7 @@ static int nu_uuart_receive(struct rt_serial_device *serial);
 static void nu_uuart_isr(nu_uuart_t serial);
 
 #if defined(RT_SERIAL_USING_DMA)
-    static rt_size_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+    static rt_ssize_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
     static void nu_pdma_uuart_rx_cb(void *pvOwner, uint32_t u32Events);
     static void nu_pdma_uuart_tx_cb(void *pvOwner, uint32_t u32Events);
 #endif
@@ -401,7 +401,7 @@ static void nu_pdma_uuart_tx_cb(void *pvOwner, uint32_t u32Events)
 /**
  * UUart DMA transfer
  */
-static rt_size_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     rt_err_t result = RT_EOK;
     nu_uuart_t psNuUUart = (nu_uuart_t)serial;
diff --git a/bsp/nuvoton/libraries/m460/rtt_port/emac/drv_emac.c b/bsp/nuvoton/libraries/m460/rtt_port/emac/drv_emac.c
index 7d7465b1d0..1268cef74f 100644
--- a/bsp/nuvoton/libraries/m460/rtt_port/emac/drv_emac.c
+++ b/bsp/nuvoton/libraries/m460/rtt_port/emac/drv_emac.c
@@ -488,13 +488,13 @@ static rt_err_t nu_gmac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t nu_gmac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_gmac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t nu_gmac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_gmac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_emac.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_emac.c
index 6168e3f94e..766b341e69 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_emac.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_emac.c
@@ -71,8 +71,8 @@ static rt_err_t nu_emac_init(rt_device_t dev);
 
 static rt_err_t nu_emac_open(rt_device_t dev, rt_uint16_t oflag);
 static rt_err_t nu_emac_close(rt_device_t dev);
-static rt_size_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-static rt_size_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+static rt_ssize_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+static rt_ssize_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 static rt_err_t nu_emac_control(rt_device_t dev, int cmd, void *args);
 static rt_err_t nu_emac_tx(rt_device_t dev, struct pbuf *p);
 static struct pbuf *nu_emac_rx(rt_device_t dev);
@@ -281,13 +281,13 @@ static rt_err_t nu_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_hsusbd.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_hsusbd.c
index 47329cc294..6b1b120c2e 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_hsusbd.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_hsusbd.c
@@ -403,7 +403,7 @@ __STATIC_INLINE void nu_buffer_cpy(rt_uint8_t address, void *buffer, rt_size_t s
     }
 }
 
-static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
+static rt_ssize_t _ep_read(rt_uint8_t address, void *buffer)
 {
     rt_size_t size  = 0;
 
@@ -431,7 +431,7 @@ static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
     return size;
 }
 
-static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT(!(address & USB_DIR_IN));
 
@@ -466,7 +466,7 @@ static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t si
     return size;
 }
 
-static rt_size_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
 {
 
     RT_ASSERT((address & USB_DIR_IN));
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_i2c.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_i2c.c
index b7082d1ae4..bd060964ae 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_i2c.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_i2c.c
@@ -78,7 +78,7 @@ static nu_i2c_bus_t nu_i2c2 =
 /* Private functions ------------------------------------------------------------*/
 #if (defined(BSP_USING_I2C0) || defined(BSP_USING_I2C1) || defined(BSP_USING_I2C2))
 
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num);
 static rt_err_t nu_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -226,7 +226,7 @@ static rt_err_t nu_i2c_send_address(nu_i2c_bus_t *nu_i2c,
     return RT_EOK;
 }
 
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num)
 {
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_pdma.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_pdma.c
index a0eaa3379e..8fb4cca738 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_pdma.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_pdma.c
@@ -66,7 +66,7 @@ static void nu_pdma_channel_disable(int i32ChannID);
 static void nu_pdma_channel_reset(int i32ChannID);
 static rt_err_t nu_pdma_timeout_set(int i32ChannID, int i32Timeout_us);
 static void nu_pdma_periph_ctrl_fill(int i32ChannID, int i32CtlPoolIdx);
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int count, nu_pdma_memctrl_t eMemCtl);
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int count, nu_pdma_memctrl_t eMemCtl);
 static void nu_pdma_memfun_cb(void *pvUserData, uint32_t u32Events);
 static void nu_pdma_memfun_actor_init(void);
 static int nu_pdma_memfun_employ(void);
@@ -940,7 +940,7 @@ static int nu_pdma_memfun_employ(void)
     return idx;
 }
 
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
 {
     nu_pdma_memfun_actor_t psMemFunActor = NULL;
     int idx;
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_rtc.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_rtc.c
index 49a0bc2a47..57046bd813 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_rtc.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_rtc.c
@@ -53,8 +53,8 @@
 static rt_err_t nu_rtc_control(rt_device_t dev, int cmd, void *args);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
-    static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-    static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 #endif
 
 static rt_err_t nu_rtc_is_date_valid(const time_t t);
@@ -155,7 +155,7 @@ INIT_BOARD_EXPORT(rt_hw_rtc_init);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.read() entry. */
-static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_GET_TIME, buffer);
@@ -167,7 +167,7 @@ static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_siz
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.write() entry. */
-static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_SET_TIME, (void *)buffer);
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_sdh.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_sdh.c
index 55a1f404e6..897784e60d 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_sdh.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_sdh.c
@@ -117,7 +117,7 @@ static void nu_sdh_isr(nu_sdh_t sdh);
 static rt_err_t nu_sdh_init(rt_device_t dev);
 static rt_err_t nu_sdh_open(rt_device_t dev, rt_uint16_t oflag);
 static rt_err_t nu_sdh_close(rt_device_t dev);
-static rt_size_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb);
+static rt_ssize_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb);
 static rt_err_t nu_sdh_control(rt_device_t dev, int cmd, void *args);
 static int rt_hw_sdh_init(void);
 
@@ -272,7 +272,7 @@ static rt_err_t nu_sdh_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb)
+static rt_ssize_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb)
 {
     rt_uint32_t ret = 0;
     nu_sdh_t sdh = (nu_sdh_t)dev;
@@ -334,7 +334,7 @@ exit_nu_sdh_read:
     return 0;
 }
 
-static rt_size_t nu_sdh_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t blk_nb)
+static rt_ssize_t nu_sdh_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t blk_nb)
 {
     rt_uint32_t ret = 0;
     nu_sdh_t sdh = (nu_sdh_t)dev;
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_spi.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_spi.c
index 7dfed36faf..246559393b 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_spi.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_spi.c
@@ -64,7 +64,7 @@ static rt_err_t nu_spi_bus_configure(struct rt_spi_device *device, struct rt_spi
     static void nu_pdma_spi_rx_cb(void *pvUserData, uint32_t u32EventFilter);
     static rt_err_t nu_pdma_spi_rx_config(struct nu_spi *spi_bus, uint8_t *pu8Buf, int32_t i32RcvLen, uint8_t bytes_per_word);
     static rt_err_t nu_pdma_spi_tx_config(struct nu_spi *spi_bus, const uint8_t *pu8Buf, int32_t i32SndLen, uint8_t bytes_per_word);
-    static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
+    static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
 #endif
 /* Public functions -------------------------------------------------------------*/
 void nu_spi_transfer(struct nu_spi *spi_bus, uint8_t *tx, uint8_t *rx, int length, uint8_t bytes_per_word);
@@ -360,7 +360,7 @@ exit_nu_pdma_spi_tx_config:
 /**
  * SPI PDMA transfer
  */
-static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
+static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
 {
     rt_err_t result = RT_EOK;
     rt_uint32_t u32Offset = 0;
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_uart.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_uart.c
index 609c30afeb..64b7f1dac0 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_uart.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_uart.c
@@ -85,7 +85,7 @@ static int nu_uart_receive(struct rt_serial_device *serial);
 static void nu_uart_isr(nu_uart_t serial);
 
 #if defined(RT_SERIAL_USING_DMA)
-    static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+    static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
     static void nu_pdma_uart_rx_cb(void *pvOwner, uint32_t u32Events);
     static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events);
 #endif
@@ -656,7 +656,7 @@ static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events)
 /**
  * Uart DMA transfer
  */
-static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     rt_err_t result = RT_EOK;
     nu_uart_t psNuUart = (nu_uart_t)serial;
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_ui2c.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_ui2c.c
index 2c46f637a4..f5bc4b0e70 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_ui2c.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_ui2c.c
@@ -37,7 +37,7 @@ typedef struct nu_ui2c_bus
 } nu_ui2c_bus_t;
 
 /* Private functions ------------------------------------------------------------*/
-static rt_size_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *ui2c_dev,
+static rt_ssize_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *ui2c_dev,
                                   struct rt_i2c_msg msgs[],
                                   rt_uint32_t num);
 
@@ -188,7 +188,7 @@ static rt_err_t nu_ui2c_send_address(nu_ui2c_bus_t *nu_ui2c,
     return RT_EOK;
 }
 
-static rt_size_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_ui2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                   struct rt_i2c_msg msgs[],
                                   rt_uint32_t num)
 {
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_usbd.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_usbd.c
index 2df21ac8d4..728c336fc6 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_usbd.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_usbd.c
@@ -210,7 +210,7 @@ static rt_err_t _ep_disable(uep_t ep)
     return RT_EOK;
 }
 
-static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
+static rt_ssize_t _ep_read(rt_uint8_t address, void *buffer)
 {
     rt_size_t size = 0;
     rt_uint8_t *buf;
@@ -226,7 +226,7 @@ static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
     return size;
 }
 
-static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT(!(address & USB_DIR_IN));
 
@@ -235,7 +235,7 @@ static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t si
     return size;
 }
 
-static rt_size_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT((address & USB_DIR_IN));
 
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_uspi.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_uspi.c
index ee47936b03..21e133b3e4 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_uspi.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_uspi.c
@@ -78,7 +78,7 @@ static void nu_uspi_drain_rxfifo(USPI_T *uspi_base);
     static void nu_pdma_uspi_rx_cb(void *pvUserData, uint32_t u32EventFilter);
     static rt_err_t nu_pdma_uspi_rx_config(struct nu_uspi *uspi_bus, uint8_t *pu8Buf, int32_t i32RcvLen, uint8_t bytes_per_word);
     static rt_err_t nu_pdma_uspi_tx_config(struct nu_uspi *uspi_bus, const uint8_t *pu8Buf, int32_t i32SndLen, uint8_t bytes_per_word);
-    static rt_size_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
+    static rt_ssize_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
     static rt_err_t nu_hw_uspi_pdma_allocate(struct nu_uspi *uspi_bus);
 #endif
 /* Public functions -------------------------------------------------------------*/
@@ -341,7 +341,7 @@ exit_nu_pdma_uspi_tx_config:
 /**
  * USPI PDMA transfer
  **/
-static rt_size_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
+static rt_ssize_t nu_uspi_pdma_transmit(struct nu_uspi *uspi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
 {
     rt_err_t result = RT_EOK;
     rt_uint32_t u32Offset = 0;
diff --git a/bsp/nuvoton/libraries/m480/rtt_port/drv_uuart.c b/bsp/nuvoton/libraries/m480/rtt_port/drv_uuart.c
index 1cd9e5a717..925b86ffad 100644
--- a/bsp/nuvoton/libraries/m480/rtt_port/drv_uuart.c
+++ b/bsp/nuvoton/libraries/m480/rtt_port/drv_uuart.c
@@ -64,7 +64,7 @@ static int nu_uuart_receive(struct rt_serial_device *serial);
 static void nu_uuart_isr(nu_uuart_t serial);
 
 #if defined(RT_SERIAL_USING_DMA)
-    static rt_size_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+    static rt_ssize_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
     static void nu_pdma_uuart_rx_cb(void *pvOwner, uint32_t u32Events);
     static void nu_pdma_uuart_tx_cb(void *pvOwner, uint32_t u32Events);
 #endif
@@ -415,7 +415,7 @@ static void nu_pdma_uuart_tx_cb(void *pvOwner, uint32_t u32Events)
 /**
  * UUart DMA transfer
  */
-static rt_size_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t nu_uuart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     rt_err_t result = RT_EOK;
 
diff --git a/bsp/nuvoton/libraries/ma35/rtt_port/drv_i2c.c b/bsp/nuvoton/libraries/ma35/rtt_port/drv_i2c.c
index c4f9781681..e6fdb4675a 100644
--- a/bsp/nuvoton/libraries/ma35/rtt_port/drv_i2c.c
+++ b/bsp/nuvoton/libraries/ma35/rtt_port/drv_i2c.c
@@ -99,7 +99,7 @@ static nu_i2c_bus_t nu_i2c_arr [ ] =
 
 /* Private functions ------------------------------------------------------------*/
 #if defined(BSP_USING_I2C)
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num);
 static rt_err_t nu_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -247,7 +247,7 @@ static rt_err_t nu_i2c_send_address(nu_i2c_bus_t *nu_i2c,
     return RT_EOK;
 }
 
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num)
 {
diff --git a/bsp/nuvoton/libraries/ma35/rtt_port/drv_pdma.c b/bsp/nuvoton/libraries/ma35/rtt_port/drv_pdma.c
index a46cf355bf..2304107cd3 100644
--- a/bsp/nuvoton/libraries/ma35/rtt_port/drv_pdma.c
+++ b/bsp/nuvoton/libraries/ma35/rtt_port/drv_pdma.c
@@ -100,7 +100,7 @@ static void nu_pdma_channel_disable(int i32ChannID);
 static void nu_pdma_channel_reset(int i32ChannID);
 static rt_err_t nu_pdma_timeout_set(int i32ChannID, int i32Timeout_us);
 static void nu_pdma_periph_ctrl_fill(int i32ChannID, int i32CtlPoolIdx);
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl);
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl);
 static void nu_pdma_memfun_cb(void *pvUserData, uint32_t u32Events);
 static void nu_pdma_memfun_actor_init(void);
 static int nu_pdma_memfun_employ(void);
@@ -1175,7 +1175,7 @@ static int nu_pdma_memfun_employ(void)
     return idx;
 }
 
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
 {
     nu_pdma_memfun_actor_t psMemFunActor = NULL;
     struct nu_pdma_chn_cb sChnCB;
diff --git a/bsp/nuvoton/libraries/ma35/rtt_port/drv_rtc.c b/bsp/nuvoton/libraries/ma35/rtt_port/drv_rtc.c
index e960ae63b2..31aeed0ed3 100644
--- a/bsp/nuvoton/libraries/ma35/rtt_port/drv_rtc.c
+++ b/bsp/nuvoton/libraries/ma35/rtt_port/drv_rtc.c
@@ -55,8 +55,8 @@
 static rt_err_t nu_rtc_control(rt_device_t dev, int cmd, void *args);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
-    static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-    static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 #endif
 
 static rt_err_t nu_rtc_is_date_valid(const time_t t);
@@ -169,7 +169,7 @@ INIT_BOARD_EXPORT(rt_hw_rtc_init);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.read() entry. */
-static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_GET_TIME, buffer);
@@ -181,7 +181,7 @@ static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_siz
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.write() entry. */
-static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_SET_TIME, (void *)buffer);
diff --git a/bsp/nuvoton/libraries/ma35/rtt_port/drv_spi.c b/bsp/nuvoton/libraries/ma35/rtt_port/drv_spi.c
index e8d2a69c9d..92482cc657 100644
--- a/bsp/nuvoton/libraries/ma35/rtt_port/drv_spi.c
+++ b/bsp/nuvoton/libraries/ma35/rtt_port/drv_spi.c
@@ -64,7 +64,7 @@ static rt_err_t nu_spi_bus_configure(struct rt_spi_device *device, struct rt_spi
     static void nu_pdma_spi_rx_cb_event(void *pvUserData, uint32_t u32EventFilter);
     static rt_err_t nu_pdma_spi_rx_config(struct nu_spi *spi_bus, uint8_t *pu8Buf, int32_t i32RcvLen, uint8_t bytes_per_word);
     static rt_err_t nu_pdma_spi_tx_config(struct nu_spi *spi_bus, const uint8_t *pu8Buf, int32_t i32SndLen, uint8_t bytes_per_word);
-    static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
+    static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
 #endif
 /* Public functions -------------------------------------------------------------*/
 void nu_spi_transfer(struct nu_spi *spi_bus, uint8_t *tx, uint8_t *rx, int length, uint8_t bytes_per_word);
@@ -393,7 +393,7 @@ exit_nu_pdma_spi_tx_config:
 /**
  * SPI PDMA transfer
  */
-static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
+static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
 {
     rt_err_t result = RT_EOK;
 
diff --git a/bsp/nuvoton/libraries/ma35/rtt_port/drv_uart.c b/bsp/nuvoton/libraries/ma35/rtt_port/drv_uart.c
index 9d10050a24..8c388b09ac 100644
--- a/bsp/nuvoton/libraries/ma35/rtt_port/drv_uart.c
+++ b/bsp/nuvoton/libraries/ma35/rtt_port/drv_uart.c
@@ -130,7 +130,7 @@ static int nu_uart_send(struct rt_serial_device *serial, char c);
 static int nu_uart_receive(struct rt_serial_device *serial);
 
 #if defined(RT_SERIAL_USING_DMA)
-    static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+    static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
     static void nu_pdma_uart_rx_cb(void *pvOwner, uint32_t u32Events);
     static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events);
     static uint32_t nu_uart_flush(nu_uart_t psNuUart, uint32_t pdma_new_rxsize);
@@ -953,7 +953,7 @@ static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events)
 /**
  * Uart DMA transfer
  */
-static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     rt_err_t result = RT_EOK;
     nu_uart_t psNuUart = (nu_uart_t)serial;
diff --git a/bsp/nuvoton/libraries/ma35/rtt_port/drv_whc.c b/bsp/nuvoton/libraries/ma35/rtt_port/drv_whc.c
index b8b5899f8e..0e0baeb602 100644
--- a/bsp/nuvoton/libraries/ma35/rtt_port/drv_whc.c
+++ b/bsp/nuvoton/libraries/ma35/rtt_port/drv_whc.c
@@ -162,7 +162,7 @@ rt_err_t nu_whc_close(rt_device_t dev)
     return RT_EOK;
 }
 
-rt_size_t nu_whc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+rt_ssize_t nu_whc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     nu_whc_t psWhc = (nu_whc_t)dev;
     nu_whc_priv_t psWhcPriv = psWhc->psPriv;
@@ -180,7 +180,7 @@ exit_nu_whc_read:
     return 0;
 }
 
-rt_size_t nu_whc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+rt_ssize_t nu_whc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     nu_whc_t psWhc = (nu_whc_t)dev;
     nu_whc_priv_t psWhcPriv = psWhc->psPriv;
diff --git a/bsp/nuvoton/libraries/ma35/rtt_port/gmac/drv_gmac.c b/bsp/nuvoton/libraries/ma35/rtt_port/gmac/drv_gmac.c
index 9a7ee9ed8a..0670a8a33b 100644
--- a/bsp/nuvoton/libraries/ma35/rtt_port/gmac/drv_gmac.c
+++ b/bsp/nuvoton/libraries/ma35/rtt_port/gmac/drv_gmac.c
@@ -515,13 +515,13 @@ static rt_err_t nu_gmac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t nu_gmac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_gmac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t nu_gmac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_gmac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/nuvoton/libraries/n9h30/rtt_port/drv_emac.c b/bsp/nuvoton/libraries/n9h30/rtt_port/drv_emac.c
index f208bb87c7..8280c81bc1 100644
--- a/bsp/nuvoton/libraries/n9h30/rtt_port/drv_emac.c
+++ b/bsp/nuvoton/libraries/n9h30/rtt_port/drv_emac.c
@@ -81,8 +81,8 @@ static rt_err_t nu_emac_init(rt_device_t dev);
 
 static rt_err_t nu_emac_open(rt_device_t dev, rt_uint16_t oflag);
 static rt_err_t nu_emac_close(rt_device_t dev);
-static rt_size_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-static rt_size_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+static rt_ssize_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+static rt_ssize_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 static rt_err_t nu_emac_control(rt_device_t dev, int cmd, void *args);
 static rt_err_t nu_emac_tx(rt_device_t dev, struct pbuf *p);
 static struct pbuf *nu_emac_rx(rt_device_t dev);
@@ -350,13 +350,13 @@ static rt_err_t nu_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/nuvoton/libraries/n9h30/rtt_port/drv_i2c.c b/bsp/nuvoton/libraries/n9h30/rtt_port/drv_i2c.c
index 987f8b3fd5..9196a6f550 100644
--- a/bsp/nuvoton/libraries/n9h30/rtt_port/drv_i2c.c
+++ b/bsp/nuvoton/libraries/n9h30/rtt_port/drv_i2c.c
@@ -459,7 +459,7 @@ static int32_t nu_i2c_ioctl(nu_i2c_dev_t psNuI2cDev, uint32_t cmd, uint32_t arg0
     return (0);
 }
 
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num)
 {
diff --git a/bsp/nuvoton/libraries/n9h30/rtt_port/drv_rtc.c b/bsp/nuvoton/libraries/n9h30/rtt_port/drv_rtc.c
index dde3b75ebf..35cb9aae83 100644
--- a/bsp/nuvoton/libraries/n9h30/rtt_port/drv_rtc.c
+++ b/bsp/nuvoton/libraries/n9h30/rtt_port/drv_rtc.c
@@ -54,8 +54,8 @@
 static rt_err_t nu_rtc_control(rt_device_t dev, int cmd, void *args);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
-    static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-    static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 #endif
 
 static rt_err_t nu_rtc_is_date_valid(const time_t t);
@@ -174,7 +174,7 @@ INIT_BOARD_EXPORT(rt_hw_rtc_init);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.read() entry. */
-static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_GET_TIME, buffer);
@@ -186,7 +186,7 @@ static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_siz
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.write() entry. */
-static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_SET_TIME, (void *)buffer);
diff --git a/bsp/nuvoton/libraries/n9h30/rtt_port/drv_sdh.c b/bsp/nuvoton/libraries/n9h30/rtt_port/drv_sdh.c
index 2ead28d452..1cbfbfb3ba 100644
--- a/bsp/nuvoton/libraries/n9h30/rtt_port/drv_sdh.c
+++ b/bsp/nuvoton/libraries/n9h30/rtt_port/drv_sdh.c
@@ -131,7 +131,7 @@ typedef struct nu_sdh *nu_sdh_t;
 static rt_err_t nu_sdh_init(rt_device_t dev);
 static rt_err_t nu_sdh_open(rt_device_t dev, rt_uint16_t oflag);
 static rt_err_t nu_sdh_close(rt_device_t dev);
-static rt_size_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb);
+static rt_ssize_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb);
 static rt_err_t nu_sdh_control(rt_device_t dev, int cmd, void *args);
 static int rt_hw_sdh_init(void);
 
@@ -344,7 +344,7 @@ static rt_err_t nu_sdh_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb)
+static rt_ssize_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb)
 {
     rt_err_t result = RT_ERROR;
     rt_uint32_t ret = 0;
@@ -426,7 +426,7 @@ exit_nu_sdh_read:
     return 0;
 }
 
-static rt_size_t nu_sdh_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t blk_nb)
+static rt_ssize_t nu_sdh_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t blk_nb)
 {
     rt_err_t result = RT_ERROR;
     rt_uint32_t ret = 0;
diff --git a/bsp/nuvoton/libraries/n9h30/rtt_port/drv_usbd.c b/bsp/nuvoton/libraries/n9h30/rtt_port/drv_usbd.c
index 876c6d96c2..870e9bb9f0 100644
--- a/bsp/nuvoton/libraries/n9h30/rtt_port/drv_usbd.c
+++ b/bsp/nuvoton/libraries/n9h30/rtt_port/drv_usbd.c
@@ -436,7 +436,7 @@ __STATIC_INLINE void nu_buffer_cpy(rt_uint8_t address, void *buffer, rt_size_t s
     }
 }
 
-static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
+static rt_ssize_t _ep_read(rt_uint8_t address, void *buffer)
 {
     rt_size_t size  = 0;
 
@@ -464,7 +464,7 @@ static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
     return size;
 }
 
-static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT(!(address & USB_DIR_IN));
 
@@ -496,7 +496,7 @@ static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t si
     return size;
 }
 
-static rt_size_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
 {
 
     RT_ASSERT((address & USB_DIR_IN));
diff --git a/bsp/nuvoton/libraries/nu_packages/ADC_TOUCH/adc_touch.c b/bsp/nuvoton/libraries/nu_packages/ADC_TOUCH/adc_touch.c
index 5d9951e968..6a687144ca 100644
--- a/bsp/nuvoton/libraries/nu_packages/ADC_TOUCH/adc_touch.c
+++ b/bsp/nuvoton/libraries/nu_packages/ADC_TOUCH/adc_touch.c
@@ -162,7 +162,7 @@ static void nu_adc_touch_cal(int32_t *sumx, int32_t *sumy)
              g_sCalMat.e * ytemp) / g_sCalMat.div;
 }
 
-static rt_size_t nu_adc_touch_readpoint(struct rt_touch_device *device, void *buf, rt_size_t read_num)
+static rt_ssize_t nu_adc_touch_readpoint(struct rt_touch_device *device, void *buf, rt_size_t read_num)
 {
     static uint32_t last_report_x = 0, last_report_y = 0;
     struct rt_touch_data *pPoint = (struct rt_touch_data *)buf;
diff --git a/bsp/nuvoton/libraries/nu_packages/ILI_TPC/ili.c b/bsp/nuvoton/libraries/nu_packages/ILI_TPC/ili.c
index 434f07bad5..e8b48bf2e6 100644
--- a/bsp/nuvoton/libraries/nu_packages/ILI_TPC/ili.c
+++ b/bsp/nuvoton/libraries/nu_packages/ILI_TPC/ili.c
@@ -381,7 +381,7 @@ static void ili_touch_down(void *buf, int8_t id, int16_t x, int16_t y, int16_t w
     pre_w[id] = w;
 }
 
-static rt_size_t ili_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
+static rt_ssize_t ili_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
 {
 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
 
diff --git a/bsp/nuvoton/libraries/nu_packages/TPC/ft5446.c b/bsp/nuvoton/libraries/nu_packages/TPC/ft5446.c
index e65e412a74..82a760dcb7 100644
--- a/bsp/nuvoton/libraries/nu_packages/TPC/ft5446.c
+++ b/bsp/nuvoton/libraries/nu_packages/TPC/ft5446.c
@@ -132,7 +132,7 @@ static int8_t pre_id[FT_MAX_TOUCH];
 static S_FT_REGMAP sFtRegMap;
 static rt_uint8_t pre_touch = 0;
 
-static rt_size_t ft5446_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
+static rt_ssize_t ft5446_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
 {
     int i;
 
diff --git a/bsp/nuvoton/libraries/nu_packages/TPC/gt911.c b/bsp/nuvoton/libraries/nu_packages/TPC/gt911.c
index 4958d1713a..e3afd090da 100644
--- a/bsp/nuvoton/libraries/nu_packages/TPC/gt911.c
+++ b/bsp/nuvoton/libraries/nu_packages/TPC/gt911.c
@@ -200,7 +200,7 @@ static void gt911_touch_down(void *buf, rt_int8_t id, rt_int16_t x, rt_int16_t y
 static rt_int8_t pre_id[GT911_MAX_TOUCH];
 static rt_uint8_t pre_touch = 0;
 
-static rt_size_t gt911_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
+static rt_ssize_t gt911_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
 {
     rt_uint8_t point_status = 0;
     rt_uint8_t touch_num = 0;
diff --git a/bsp/nuvoton/libraries/nu_packages/TPC/ili.c b/bsp/nuvoton/libraries/nu_packages/TPC/ili.c
index af2d0ca12c..71d444212a 100644
--- a/bsp/nuvoton/libraries/nu_packages/TPC/ili.c
+++ b/bsp/nuvoton/libraries/nu_packages/TPC/ili.c
@@ -383,7 +383,7 @@ static void ili_touch_down(void *buf, int8_t id, int16_t x, int16_t y, int16_t w
 
 static int8_t pre_id[ILI_MAX_TOUCH];
 static rt_uint8_t pre_touch = 0;
-static rt_size_t ili_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
+static rt_ssize_t ili_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
 {
 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
 
diff --git a/bsp/nuvoton/libraries/nu_packages/TPC/st1663i.c b/bsp/nuvoton/libraries/nu_packages/TPC/st1663i.c
index a2349e8f52..33f999b5de 100644
--- a/bsp/nuvoton/libraries/nu_packages/TPC/st1663i.c
+++ b/bsp/nuvoton/libraries/nu_packages/TPC/st1663i.c
@@ -132,7 +132,7 @@ static int8_t pre_id[ST_MAX_TOUCH];
 static S_ST_REGMAP sStRegMap;
 static rt_uint8_t pre_touch = 0;
 
-static rt_size_t st1663i_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
+static rt_ssize_t st1663i_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
 {
     int i;
 
diff --git a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_emac.c b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_emac.c
index b18a84d225..da322fa8cb 100644
--- a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_emac.c
+++ b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_emac.c
@@ -93,8 +93,8 @@ static rt_err_t nu_emac_init(rt_device_t dev);
 
 static rt_err_t nu_emac_open(rt_device_t dev, rt_uint16_t oflag);
 static rt_err_t nu_emac_close(rt_device_t dev);
-static rt_size_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-static rt_size_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+static rt_ssize_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+static rt_ssize_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 static rt_err_t nu_emac_control(rt_device_t dev, int cmd, void *args);
 static rt_err_t nu_emac_tx(rt_device_t dev, struct pbuf *p);
 static struct pbuf *nu_emac_rx(rt_device_t dev);
@@ -372,13 +372,13 @@ static rt_err_t nu_emac_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_emac_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_emac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_i2c.c b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_i2c.c
index 89e80b662f..79249bedfc 100644
--- a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_i2c.c
+++ b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_i2c.c
@@ -97,7 +97,7 @@ static nu_i2c_bus_t nu_i2c_arr [ ] =
 
 /* Private functions ------------------------------------------------------------*/
 #if defined(BSP_USING_I2C)
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num);
 static rt_err_t nu_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -245,7 +245,7 @@ static rt_err_t nu_i2c_send_address(nu_i2c_bus_t *nu_i2c,
     return RT_EOK;
 }
 
-static rt_size_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t nu_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num)
 {
diff --git a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_pdma.c b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_pdma.c
index 6452752b1a..4468a6744b 100644
--- a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_pdma.c
+++ b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_pdma.c
@@ -75,7 +75,7 @@ static void nu_pdma_channel_disable(int i32ChannID);
 static void nu_pdma_channel_reset(int i32ChannID);
 static rt_err_t nu_pdma_timeout_set(int i32ChannID, int i32Timeout_us);
 static void nu_pdma_periph_ctrl_fill(int i32ChannID, int i32CtlPoolIdx);
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl);
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl);
 static void nu_pdma_memfun_cb(void *pvUserData, uint32_t u32Events);
 static void nu_pdma_memfun_actor_init(void);
 static int nu_pdma_memfun_employ(void);
@@ -1028,7 +1028,7 @@ static int nu_pdma_memfun_employ(void)
     return idx;
 }
 
-static rt_size_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
+static rt_ssize_t nu_pdma_memfun(void *dest, void *src, uint32_t u32DataWidth, unsigned int u32TransferCnt, nu_pdma_memctrl_t eMemCtl)
 {
     nu_pdma_memfun_actor_t psMemFunActor = NULL;
     struct nu_pdma_chn_cb sChnCB;
diff --git a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_rtc.c b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_rtc.c
index fc0a2dc7bb..326cdffaf4 100644
--- a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_rtc.c
+++ b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_rtc.c
@@ -54,8 +54,8 @@
 static rt_err_t nu_rtc_control(rt_device_t dev, int cmd, void *args);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
-    static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-    static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+    static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 #endif
 
 static rt_err_t nu_rtc_is_date_valid(const time_t t);
@@ -156,7 +156,7 @@ INIT_BOARD_EXPORT(rt_hw_rtc_init);
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.read() entry. */
-static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_GET_TIME, buffer);
@@ -168,7 +168,7 @@ static rt_size_t nu_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_siz
 
 #if defined (NU_RTC_SUPPORT_IO_RW)
 /* Register rt-thread device.write() entry. */
-static rt_size_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t nu_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     (void) pos;
     nu_rtc_control(dev, RT_DEVICE_CTRL_RTC_SET_TIME, (void *)buffer);
diff --git a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_sdh.c b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_sdh.c
index bc3b23fd0d..6e6aeca4d5 100644
--- a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_sdh.c
+++ b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_sdh.c
@@ -117,7 +117,7 @@ typedef struct nu_sdh *nu_sdh_t;
 static rt_err_t nu_sdh_init(rt_device_t dev);
 static rt_err_t nu_sdh_open(rt_device_t dev, rt_uint16_t oflag);
 static rt_err_t nu_sdh_close(rt_device_t dev);
-static rt_size_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb);
+static rt_ssize_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb);
 static rt_err_t nu_sdh_control(rt_device_t dev, int cmd, void *args);
 static int rt_hw_sdh_init(void);
 
@@ -251,7 +251,7 @@ static rt_err_t nu_sdh_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb)
+static rt_ssize_t nu_sdh_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t blk_nb)
 {
     rt_err_t result = RT_ERROR;
     rt_uint32_t ret = 0;
@@ -317,7 +317,7 @@ exit_nu_sdh_read:
     return 0;
 }
 
-static rt_size_t nu_sdh_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t blk_nb)
+static rt_ssize_t nu_sdh_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t blk_nb)
 {
     rt_err_t result = RT_ERROR;
     rt_uint32_t ret = 0;
diff --git a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_spi.c b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_spi.c
index e4d69798a3..6f4dd0e2fb 100644
--- a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_spi.c
+++ b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_spi.c
@@ -63,7 +63,7 @@ static rt_err_t nu_spi_bus_configure(struct rt_spi_device *device, struct rt_spi
     static void nu_pdma_spi_rx_cb_event(void *pvUserData, uint32_t u32EventFilter);
     static rt_err_t nu_pdma_spi_rx_config(struct nu_spi *spi_bus, uint8_t *pu8Buf, int32_t i32RcvLen, uint8_t bytes_per_word);
     static rt_err_t nu_pdma_spi_tx_config(struct nu_spi *spi_bus, const uint8_t *pu8Buf, int32_t i32SndLen, uint8_t bytes_per_word);
-    static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
+    static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word);
 #endif
 /* Public functions -------------------------------------------------------------*/
 void nu_spi_transfer(struct nu_spi *spi_bus, uint8_t *tx, uint8_t *rx, int length, uint8_t bytes_per_word);
@@ -363,7 +363,7 @@ exit_nu_pdma_spi_tx_config:
 /**
  * SPI PDMA transfer
  */
-static rt_size_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
+static rt_ssize_t nu_spi_pdma_transmit(struct nu_spi *spi_bus, const uint8_t *send_addr, uint8_t *recv_addr, int length, uint8_t bytes_per_word)
 {
     rt_err_t result = RT_EOK;
 
diff --git a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_uart.c b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_uart.c
index b6677ab453..afb1c75f7c 100644
--- a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_uart.c
+++ b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_uart.c
@@ -95,7 +95,7 @@ static int nu_uart_send(struct rt_serial_device *serial, char c);
 static int nu_uart_receive(struct rt_serial_device *serial);
 
 #if defined(RT_SERIAL_USING_DMA)
-    static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+    static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
     static void nu_pdma_uart_rx_cb(void *pvOwner, uint32_t u32Events);
     static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events);
 #endif
@@ -673,7 +673,7 @@ static void nu_pdma_uart_tx_cb(void *pvOwner, uint32_t u32Events)
 /**
  * Uart DMA transfer
  */
-static rt_size_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t nu_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     rt_err_t result = RT_EOK;
     nu_uart_t psNuUart = (nu_uart_t)serial;
diff --git a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_usbd.c b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_usbd.c
index ae563d1a1e..d12fac21fa 100644
--- a/bsp/nuvoton/libraries/nuc980/rtt_port/drv_usbd.c
+++ b/bsp/nuvoton/libraries/nuc980/rtt_port/drv_usbd.c
@@ -437,7 +437,7 @@ __STATIC_INLINE void nu_buffer_cpy(rt_uint8_t address, void *buffer, rt_size_t s
     }
 }
 
-static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
+static rt_ssize_t _ep_read(rt_uint8_t address, void *buffer)
 {
     rt_size_t size  = 0;
 
@@ -465,7 +465,7 @@ static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
     return size;
 }
 
-static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     RT_ASSERT(!(address & USB_DIR_IN));
 
@@ -497,7 +497,7 @@ static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t si
     return size;
 }
 
-static rt_size_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
 {
 
     RT_ASSERT((address & USB_DIR_IN));
diff --git a/bsp/pic32ethernet/uart.c b/bsp/pic32ethernet/uart.c
index 05337aa5eb..1980426a74 100644
--- a/bsp/pic32ethernet/uart.c
+++ b/bsp/pic32ethernet/uart.c
@@ -56,7 +56,7 @@ static rt_err_t rt_uart_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     struct rt_uart_pic32 *uart_device = (struct rt_uart_pic32*)dev;
@@ -103,7 +103,7 @@ static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_si
     return 0;
 }
 
-static rt_size_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     struct rt_uart_pic32 *uart_device = (struct rt_uart_pic32*)dev;
     char *ptr;
diff --git a/bsp/qemu-vexpress-a9/drivers/audio/drv_sound.c b/bsp/qemu-vexpress-a9/drivers/audio/drv_sound.c
index 226a2cdb51..59661d0ca8 100644
--- a/bsp/qemu-vexpress-a9/drivers/audio/drv_sound.c
+++ b/bsp/qemu-vexpress-a9/drivers/audio/drv_sound.c
@@ -290,7 +290,7 @@ static void sound_buffer_info(struct rt_audio_device *audio, struct rt_audio_buf
     info->block_count = 2;
 }
 
-static rt_size_t sound_transmit(struct rt_audio_device *audio, const void *writeBuf, void *readBuf, rt_size_t size)
+static rt_ssize_t sound_transmit(struct rt_audio_device *audio, const void *writeBuf, void *readBuf, rt_size_t size)
 {
     RT_ASSERT(audio != RT_NULL);
 
diff --git a/bsp/qemu-virt64-aarch64/drivers/drv_rtc.c b/bsp/qemu-virt64-aarch64/drivers/drv_rtc.c
index d33533a10b..2b26429dcf 100644
--- a/bsp/qemu-virt64-aarch64/drivers/drv_rtc.c
+++ b/bsp/qemu-virt64-aarch64/drivers/drv_rtc.c
@@ -78,13 +78,13 @@ static rt_err_t pl031_rtc_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t pl031_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t pl031_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     pl031_rtc_control(dev, RT_DEVICE_CTRL_RTC_GET_TIME, buffer);
     return size;
 }
 
-static rt_size_t pl031_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t pl031_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     pl031_rtc_control(dev, RT_DEVICE_CTRL_RTC_SET_TIME, (void *)buffer);
     return size;
diff --git a/bsp/raspberry-pi/raspi3-32/driver/drv_i2c.c b/bsp/raspberry-pi/raspi3-32/driver/drv_i2c.c
index c7867969a1..3cf4cd2402 100644
--- a/bsp/raspberry-pi/raspi3-32/driver/drv_i2c.c
+++ b/bsp/raspberry-pi/raspi3-32/driver/drv_i2c.c
@@ -103,10 +103,10 @@ struct raspi_i2c_hw_config
 
 #if (defined(BSP_USING_I2C0) || defined(BSP_USING_I2C1))
 
-static rt_size_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num);
-static rt_size_t raspi_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t raspi_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num);
 static rt_err_t raspi_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -114,7 +114,7 @@ static rt_err_t raspi_i2c_bus_control(struct rt_i2c_bus_device *bus,
                                       rt_uint32_t);
 
 static rt_uint32_t i2c_byte_wait_us = 0;
-static rt_size_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num)
 {
@@ -141,7 +141,7 @@ static rt_size_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
     return (reason == 0)? i : 0;
 }
 
-static rt_size_t raspi_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t raspi_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num)
 {
diff --git a/bsp/raspberry-pi/raspi3-32/driver/drv_rtc.c b/bsp/raspberry-pi/raspi3-32/driver/drv_rtc.c
index 139f6f3abd..0b465b5763 100644
--- a/bsp/raspberry-pi/raspi3-32/driver/drv_rtc.c
+++ b/bsp/raspberry-pi/raspi3-32/driver/drv_rtc.c
@@ -249,13 +249,13 @@ static rt_err_t raspi_rtc_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t raspi_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t raspi_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     raspi_rtc_control(dev, RT_DEVICE_CTRL_RTC_GET_TIME, buffer);
     return size;
 }
 
-static rt_size_t raspi_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t raspi_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     raspi_rtc_control(dev, RT_DEVICE_CTRL_RTC_SET_TIME, (void *)buffer);
     return size;
diff --git a/bsp/raspberry-pi/raspi3-64/driver/drv_i2c.c b/bsp/raspberry-pi/raspi3-64/driver/drv_i2c.c
index 1f19a3bc2a..07ea8087e6 100644
--- a/bsp/raspberry-pi/raspi3-64/driver/drv_i2c.c
+++ b/bsp/raspberry-pi/raspi3-64/driver/drv_i2c.c
@@ -108,10 +108,10 @@ struct raspi_i2c_hw_config
 
 #if (defined(BSP_USING_I2C0) || defined(BSP_USING_I2C1))
 
-static rt_size_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num);
-static rt_size_t raspi_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t raspi_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num);
 static rt_err_t raspi_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -119,7 +119,7 @@ static rt_err_t raspi_i2c_bus_control(struct rt_i2c_bus_device *bus,
                                       rt_uint32_t);
 
 static rt_uint32_t i2c_byte_wait_us = 0;
-static rt_size_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num)
 {
@@ -146,7 +146,7 @@ static rt_size_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
     return (reason == 0)? i : 0;
 }
 
-static rt_size_t raspi_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t raspi_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num)
 {
diff --git a/bsp/raspberry-pi/raspi3-64/driver/drv_rtc.c b/bsp/raspberry-pi/raspi3-64/driver/drv_rtc.c
index 55848c22bc..d772614971 100644
--- a/bsp/raspberry-pi/raspi3-64/driver/drv_rtc.c
+++ b/bsp/raspberry-pi/raspi3-64/driver/drv_rtc.c
@@ -93,13 +93,13 @@ static rt_err_t raspi_rtc_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t raspi_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t raspi_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     raspi_rtc_control(dev, RT_DEVICE_CTRL_RTC_GET_TIME, buffer);
     return size;
 }
 
-static rt_size_t raspi_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t raspi_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     raspi_rtc_control(dev, RT_DEVICE_CTRL_RTC_SET_TIME, (void *)buffer);
     return size;
diff --git a/bsp/raspberry-pi/raspi4-32/driver/drv_i2c.c b/bsp/raspberry-pi/raspi4-32/driver/drv_i2c.c
index 3a7503a04d..0a9b93b99f 100644
--- a/bsp/raspberry-pi/raspi4-32/driver/drv_i2c.c
+++ b/bsp/raspberry-pi/raspi4-32/driver/drv_i2c.c
@@ -131,7 +131,7 @@ rt_uint8_t i2c_read_or_write(volatile rt_uint32_t base, rt_uint8_t* buf, rt_uint
     return reason;
 }
 
-static rt_size_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num)
 {
@@ -154,7 +154,7 @@ static rt_size_t raspi_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
     return (reason == 0)? i : 0;
 }
 
-static rt_size_t raspi_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t raspi_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
                                     struct rt_i2c_msg msgs[],
                                     rt_uint32_t num)
 {
diff --git a/bsp/raspberry-pi/raspi4-32/driver/touch/drv_dsi_touch.c b/bsp/raspberry-pi/raspi4-32/driver/touch/drv_dsi_touch.c
index 3f9dbb83ad..66e10f867b 100644
--- a/bsp/raspberry-pi/raspi4-32/driver/touch/drv_dsi_touch.c
+++ b/bsp/raspberry-pi/raspi4-32/driver/touch/drv_dsi_touch.c
@@ -77,7 +77,7 @@ static void dsi_touch_thread_entry(void *param)
     }
 }
 
-static rt_size_t dsi_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
+static rt_ssize_t dsi_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
 {
     rt_uint16_t* touchxy = (rt_uint16_t *)buf;
     if((read_num != 0) && (touch_state == 1))
diff --git a/bsp/raspberry-pi/raspi4-32/driver/touch/drv_xpt2046.c b/bsp/raspberry-pi/raspi4-32/driver/touch/drv_xpt2046.c
index 5911b5b6e3..84d72c0242 100644
--- a/bsp/raspberry-pi/raspi4-32/driver/touch/drv_xpt2046.c
+++ b/bsp/raspberry-pi/raspi4-32/driver/touch/drv_xpt2046.c
@@ -191,7 +191,7 @@ static void touch_readly(void *args)
     }
 }
 
-static rt_size_t xpt2046_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
+static rt_ssize_t xpt2046_read_point(struct rt_touch_device *touch, void *buf, rt_size_t read_num)
 {
     rt_uint16_t* touchxy = (rt_uint16_t *)buf;
     if((read_num != 0) && (touch_flag == 1))
diff --git a/bsp/renesas/libraries/HAL_Drivers/drv_i2c.c b/bsp/renesas/libraries/HAL_Drivers/drv_i2c.c
index 375083c6f3..585f6d04ad 100644
--- a/bsp/renesas/libraries/HAL_Drivers/drv_i2c.c
+++ b/bsp/renesas/libraries/HAL_Drivers/drv_i2c.c
@@ -69,7 +69,7 @@ static fsp_err_t validate_i2c_event(void)
     return FSP_ERR_TRANSFER_ABORTED;
 }
 
-static rt_size_t ra_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t ra_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                 struct rt_i2c_msg msgs[],
                                 rt_uint32_t num)
 {
diff --git a/bsp/renesas/libraries/HAL_Drivers/drv_usart_v2.c b/bsp/renesas/libraries/HAL_Drivers/drv_usart_v2.c
index 63e7716985..e36cf90491 100644
--- a/bsp/renesas/libraries/HAL_Drivers/drv_usart_v2.c
+++ b/bsp/renesas/libraries/HAL_Drivers/drv_usart_v2.c
@@ -244,7 +244,7 @@ static int ra_uart_getc(struct rt_serial_device *serial)
     return RT_EOK;
 }
 
-static rt_size_t ra_uart_transmit(struct rt_serial_device     *serial,
+static rt_ssize_t ra_uart_transmit(struct rt_serial_device     *serial,
                                   rt_uint8_t           *buf,
                                   rt_size_t             size,
                                   rt_uint32_t           tx_flag)
diff --git a/bsp/rv32m1_vega/ri5cy/driver/drv_sdcard.c b/bsp/rv32m1_vega/ri5cy/driver/drv_sdcard.c
index dda334ad18..f8217cb796 100644
--- a/bsp/rv32m1_vega/ri5cy/driver/drv_sdcard.c
+++ b/bsp/rv32m1_vega/ri5cy/driver/drv_sdcard.c
@@ -35,7 +35,7 @@ static rt_err_t vega_sdcard_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t vega_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t vega_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     status_t status;
 
@@ -47,7 +47,7 @@ static rt_size_t vega_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, r
     return 0;
 }
 
-static rt_size_t vega_sdcard_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t vega_sdcard_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     status_t status;
 
diff --git a/bsp/rv32m1_vega/ri5cy/driver/drv_uart.c b/bsp/rv32m1_vega/ri5cy/driver/drv_uart.c
index 9375c3547e..db526556e0 100644
--- a/bsp/rv32m1_vega/ri5cy/driver/drv_uart.c
+++ b/bsp/rv32m1_vega/ri5cy/driver/drv_uart.c
@@ -31,7 +31,7 @@ static rt_err_t  uart_configure(struct rt_serial_device *serial, struct serial_c
 static rt_err_t  uart_control(struct rt_serial_device *serial, int cmd, void *arg);
 static int       uart_putc(struct rt_serial_device *serial, char c);
 static int       uart_getc(struct rt_serial_device *serial);
-static rt_size_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+static rt_ssize_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
 
 static void     uart_irq_handler(int irqno, void *param);
 
@@ -228,7 +228,7 @@ static int uart_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     return (0);
 }
diff --git a/bsp/sam7x/drivers/sd.c b/bsp/sam7x/drivers/sd.c
index f024f017ab..2b5cec0d32 100644
--- a/bsp/sam7x/drivers/sd.c
+++ b/bsp/sam7x/drivers/sd.c
@@ -451,7 +451,7 @@ static rt_err_t rt_sdcard_close(rt_device_t dev)
 	return RT_EOK;
 }
 
-static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
 	rt_uint8_t count;
 
@@ -500,7 +500,7 @@ static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_
 	return size / 512;
 }
 
-static rt_size_t rt_sdcard_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
 	rt_uint8_t count;
 
diff --git a/bsp/sam7x/drivers/serial.c b/bsp/sam7x/drivers/serial.c
index 48fe49fed8..896e00ac22 100644
--- a/bsp/sam7x/drivers/serial.c
+++ b/bsp/sam7x/drivers/serial.c
@@ -218,7 +218,7 @@ static rt_err_t rt_serial_close(rt_device_t dev)
 	return RT_EOK;
 }
 
-static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
 	rt_uint8_t* ptr;
 	struct rt_at91serial *serial = (struct rt_at91serial*)dev;
@@ -287,7 +287,7 @@ static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt
 	return 0;
 }
 
-static rt_size_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
 	rt_uint8_t* ptr;
 	struct rt_at91serial *serial = (struct rt_at91serial*)dev;
diff --git a/bsp/simulator/drivers/dfs_win32.c b/bsp/simulator/drivers/dfs_win32.c
index 5edb2b211c..6d144fe6e5 100644
--- a/bsp/simulator/drivers/dfs_win32.c
+++ b/bsp/simulator/drivers/dfs_win32.c
@@ -537,7 +537,7 @@ static rt_err_t nop_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t nop_read(rt_device_t dev,
+static rt_ssize_t nop_read(rt_device_t dev,
                           rt_off_t    pos,
                           void       *buffer,
                           rt_size_t   size)
@@ -545,7 +545,7 @@ static rt_size_t nop_read(rt_device_t dev,
     return size;
 }
 
-static rt_size_t nop_write(rt_device_t dev,
+static rt_ssize_t nop_write(rt_device_t dev,
                            rt_off_t    pos,
                            const void *buffer,
                            rt_size_t   size)
diff --git a/bsp/simulator/drivers/sd_sim.c b/bsp/simulator/drivers/sd_sim.c
index 86ed57aea8..6079f23e3c 100755
--- a/bsp/simulator/drivers/sd_sim.c
+++ b/bsp/simulator/drivers/sd_sim.c
@@ -52,7 +52,7 @@ static rt_err_t rt_sdcard_close(rt_device_t dev)
  * buffer:
  * size  : how many blocks
  */
-static rt_size_t rt_sdcard_read(rt_device_t device, rt_off_t position, void *buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_read(rt_device_t device, rt_off_t position, void *buffer, rt_size_t size)
 {
     struct sdcard_device *sd;
     int result = 0;
@@ -80,7 +80,7 @@ _err:
  * buffer:
  * size  : how many blocks
  */
-static rt_size_t rt_sdcard_write(rt_device_t device, rt_off_t position, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_write(rt_device_t device, rt_off_t position, const void *buffer, rt_size_t size)
 {
     struct sdcard_device *sd;
     int result = 0;
diff --git a/bsp/simulator/pcap/pcap_netif.c b/bsp/simulator/pcap/pcap_netif.c
index 0aef477185..0ac00e4b1e 100644
--- a/bsp/simulator/pcap/pcap_netif.c
+++ b/bsp/simulator/pcap/pcap_netif.c
@@ -160,13 +160,13 @@ static rt_err_t pcap_netif_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t pcap_netif_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t pcap_netif_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t pcap_netif_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t pcap_netif_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/stm32/libraries/HAL_Drivers/drv_eth.c b/bsp/stm32/libraries/HAL_Drivers/drv_eth.c
index 3dcfe389a1..b6f71fae8c 100644
--- a/bsp/stm32/libraries/HAL_Drivers/drv_eth.c
+++ b/bsp/stm32/libraries/HAL_Drivers/drv_eth.c
@@ -152,14 +152,14 @@ static rt_err_t rt_stm32_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_stm32_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_stm32_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     LOG_D("emac read");
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_stm32_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_stm32_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     LOG_D("emac write");
     rt_set_errno(-RT_ENOSYS);
diff --git a/bsp/stm32/libraries/HAL_Drivers/drv_nand.c b/bsp/stm32/libraries/HAL_Drivers/drv_nand.c
index 3cb293a932..66280e9496 100644
--- a/bsp/stm32/libraries/HAL_Drivers/drv_nand.c
+++ b/bsp/stm32/libraries/HAL_Drivers/drv_nand.c
@@ -120,7 +120,7 @@ rt_err_t  rt_nand_control(rt_device_t dev, int cmd, void *args)
 }
 
 /*pos: sector offset   size: page count*/
-rt_size_t rt_nand_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+rt_ssize_t rt_nand_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     uint32_t page_cnt = size;
     NAND_AddressTypeDef ReadAddr;
@@ -131,7 +131,7 @@ rt_size_t rt_nand_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t si
     return RT_EOK;
 }
 
-rt_size_t rt_nand_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+rt_ssize_t rt_nand_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     uint32_t page_cnt = size;
     NAND_AddressTypeDef WriteAddr;
diff --git a/bsp/stm32/libraries/HAL_Drivers/drv_usart.c b/bsp/stm32/libraries/HAL_Drivers/drv_usart.c
index cb023a7e03..6569872ef8 100644
--- a/bsp/stm32/libraries/HAL_Drivers/drv_usart.c
+++ b/bsp/stm32/libraries/HAL_Drivers/drv_usart.c
@@ -341,7 +341,7 @@ static int stm32_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t stm32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t stm32_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     struct stm32_uart *uart;
     RT_ASSERT(serial != RT_NULL);
diff --git a/bsp/stm32/libraries/HAL_Drivers/drv_usart_v2.c b/bsp/stm32/libraries/HAL_Drivers/drv_usart_v2.c
index 2225d02572..486a338545 100644
--- a/bsp/stm32/libraries/HAL_Drivers/drv_usart_v2.c
+++ b/bsp/stm32/libraries/HAL_Drivers/drv_usart_v2.c
@@ -369,7 +369,7 @@ static int stm32_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t stm32_transmit(struct rt_serial_device     *serial,
+static rt_ssize_t stm32_transmit(struct rt_serial_device     *serial,
                                        rt_uint8_t           *buf,
                                        rt_size_t             size,
                                        rt_uint32_t           tx_flag)
diff --git a/bsp/stm32/libraries/HAL_Drivers/drv_usbd.c b/bsp/stm32/libraries/HAL_Drivers/drv_usbd.c
index bf577aa943..6acfad2099 100644
--- a/bsp/stm32/libraries/HAL_Drivers/drv_usbd.c
+++ b/bsp/stm32/libraries/HAL_Drivers/drv_usbd.c
@@ -166,20 +166,20 @@ static rt_err_t _ep_disable(uep_t ep)
     return RT_EOK;
 }
 
-static rt_size_t _ep_read(rt_uint8_t address, void *buffer)
+static rt_ssize_t _ep_read(rt_uint8_t address, void *buffer)
 {
     rt_size_t size = 0;
     RT_ASSERT(buffer != RT_NULL);
     return size;
 }
 
-static rt_size_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_read_prepare(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     HAL_PCD_EP_Receive(&_stm_pcd, address, buffer, size);
     return size;
 }
 
-static rt_size_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t _ep_write(rt_uint8_t address, void *buffer, rt_size_t size)
 {
     HAL_PCD_EP_Transmit(&_stm_pcd, address, buffer, size);
     return size;
diff --git a/bsp/stm32/stm32f407-atk-explorer/board/ports/touch/drv_touch_xpt.c b/bsp/stm32/stm32f407-atk-explorer/board/ports/touch/drv_touch_xpt.c
index ee33ee4873..204f393038 100644
--- a/bsp/stm32/stm32f407-atk-explorer/board/ports/touch/drv_touch_xpt.c
+++ b/bsp/stm32/stm32f407-atk-explorer/board/ports/touch/drv_touch_xpt.c
@@ -151,7 +151,7 @@ rt_err_t xpt2046_calibration(const char *lcd_name,const char *touch_name)
     return RT_EOK;
 }
 
-static rt_size_t xpt2046_touch_readpoint(struct rt_touch_device *touch, void *buf, rt_size_t touch_num)
+static rt_ssize_t xpt2046_touch_readpoint(struct rt_touch_device *touch, void *buf, rt_size_t touch_num)
 {
     if (touch_num != 0)
     {
diff --git a/bsp/stm32/stm32h743-atk-apollo/board/ports/drv_dcmi.c b/bsp/stm32/stm32h743-atk-apollo/board/ports/drv_dcmi.c
index cc170ff945..f4d31a43df 100644
--- a/bsp/stm32/stm32h743-atk-apollo/board/ports/drv_dcmi.c
+++ b/bsp/stm32/stm32h743-atk-apollo/board/ports/drv_dcmi.c
@@ -187,14 +187,14 @@ static rt_err_t rt_dcmi_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t rt_dcmi_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_dcmi_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
 
     return RT_EOK;
 }
 
-static rt_size_t rt_dcmi_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_dcmi_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
 
diff --git a/bsp/stm32/stm32h743-openmv-h7plus/board/ports/drv_dcmi.c b/bsp/stm32/stm32h743-openmv-h7plus/board/ports/drv_dcmi.c
index 5a115326de..1c8a328f1f 100644
--- a/bsp/stm32/stm32h743-openmv-h7plus/board/ports/drv_dcmi.c
+++ b/bsp/stm32/stm32h743-openmv-h7plus/board/ports/drv_dcmi.c
@@ -166,14 +166,14 @@ static rt_err_t rt_dcmi_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t rt_dcmi_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_dcmi_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
 
     return RT_EOK;
 }
 
-static rt_size_t rt_dcmi_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_dcmi_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
 
diff --git a/bsp/stm32/stm32h750-artpi/board/port/drv_eth.c b/bsp/stm32/stm32h750-artpi/board/port/drv_eth.c
index 8abe9ad0b3..3029aaaa4a 100644
--- a/bsp/stm32/stm32h750-artpi/board/port/drv_eth.c
+++ b/bsp/stm32/stm32h750-artpi/board/port/drv_eth.c
@@ -234,14 +234,14 @@ static rt_err_t rt_stm32_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_stm32_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_stm32_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     LOG_D("emac read");
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_stm32_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_stm32_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     LOG_D("emac write");
     rt_set_errno(-RT_ENOSYS);
diff --git a/bsp/stm32/stm32mp157a-st-discovery/board/ports/OpenAMP/drv_openamp.c b/bsp/stm32/stm32mp157a-st-discovery/board/ports/OpenAMP/drv_openamp.c
index 1d5cc5c455..9997206f01 100644
--- a/bsp/stm32/stm32mp157a-st-discovery/board/ports/OpenAMP/drv_openamp.c
+++ b/bsp/stm32/stm32mp157a-st-discovery/board/ports/OpenAMP/drv_openamp.c
@@ -115,7 +115,7 @@ static rt_err_t _init(struct rt_device *dev)
     return RT_EOK;
 }
 
-static rt_size_t _read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t _read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_size_t count, rbsize, offset;
     rt_uint8_t *buf     = RT_NULL; 
@@ -162,7 +162,7 @@ static rt_size_t _read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_siz
     return count;
 }
  
-static rt_size_t _write(struct rt_device *dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t _write(struct rt_device *dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_err_t result = VIRT_UART_OK;
     
diff --git a/bsp/stm32/stm32mp157a-st-discovery/board/ports/drv_eth.c b/bsp/stm32/stm32mp157a-st-discovery/board/ports/drv_eth.c
index 9818aca2e6..5702af3ad2 100644
--- a/bsp/stm32/stm32mp157a-st-discovery/board/ports/drv_eth.c
+++ b/bsp/stm32/stm32mp157a-st-discovery/board/ports/drv_eth.c
@@ -504,14 +504,14 @@ static rt_err_t rt_stm32_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_stm32_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_stm32_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     LOG_D("emac read");
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_stm32_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_stm32_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     LOG_D("emac write");
     rt_set_errno(-RT_ENOSYS);
diff --git a/bsp/stm32/stm32mp157a-st-ev1/board/ports/OpenAMP/drv_openamp.c b/bsp/stm32/stm32mp157a-st-ev1/board/ports/OpenAMP/drv_openamp.c
index 216a181e97..6f185bd8ac 100644
--- a/bsp/stm32/stm32mp157a-st-ev1/board/ports/OpenAMP/drv_openamp.c
+++ b/bsp/stm32/stm32mp157a-st-ev1/board/ports/OpenAMP/drv_openamp.c
@@ -115,7 +115,7 @@ static rt_err_t _init(struct rt_device *dev)
     return RT_EOK;
 }
 
-static rt_size_t _read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t _read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_size_t count, rbsize, offset;
     rt_uint8_t *buf     = RT_NULL;
@@ -162,7 +162,7 @@ static rt_size_t _read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_siz
     return count;
 }
 
-static rt_size_t _write(struct rt_device *dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t _write(struct rt_device *dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_err_t result = VIRT_UART_OK;
 
diff --git a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_dcmi.c b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_dcmi.c
index 1accaced7c..c8ff829455 100644
--- a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_dcmi.c
+++ b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_dcmi.c
@@ -167,14 +167,14 @@ static rt_err_t rt_dcmi_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t rt_dcmi_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_dcmi_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
 
     return RT_EOK;
 }
 
-static rt_size_t rt_dcmi_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_dcmi_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
 
diff --git a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_dfsdm.c b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_dfsdm.c
index 990537241e..d85a6ac22d 100644
--- a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_dfsdm.c
+++ b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_dfsdm.c
@@ -246,7 +246,7 @@ static rt_err_t _close(rt_device_t dev)
    return RT_EOK;
 }
 
-static rt_size_t _read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t _read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
     rt_uint32_t i = 0;
@@ -273,7 +273,7 @@ static rt_size_t _read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t si
     return size;
 }
 
-static rt_size_t _write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t _write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
    RT_ASSERT(dev != RT_NULL);
 
diff --git a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_fdcan.c b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_fdcan.c
index 494d8e399f..a070593536 100644
--- a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_fdcan.c
+++ b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_fdcan.c
@@ -124,7 +124,7 @@ static rt_err_t rt_fdcan_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t rt_fdcan_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_fdcan_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
     struct stm32_fdcan *device = (struct stm32_fdcan *)dev;
@@ -155,7 +155,7 @@ static rt_size_t rt_fdcan_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_s
     return 0;
 }
 
-static rt_size_t rt_fdcan_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_fdcan_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
     struct stm32_fdcan *device = (struct stm32_fdcan *)dev;
diff --git a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_sdcard.c b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_sdcard.c
index b8f524e59a..145dd200fe 100644
--- a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_sdcard.c
+++ b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_sdcard.c
@@ -203,7 +203,7 @@ static rt_err_t rt_sdcard_close(rt_device_t dev)
   * @retval DRESULT: Operation result
   */
 
-static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t sector, void *buffer, rt_size_t count)
+static rt_ssize_t rt_sdcard_read(rt_device_t dev, rt_off_t sector, void *buffer, rt_size_t count)
 {
     RT_ASSERT(dev != RT_NULL);
     struct stm32_sd *sd = (struct stm32_sd *)dev;
@@ -269,7 +269,7 @@ static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t sector, void *buffer,
   * @param  count      Number of SD blocks to write
   * @retval BSP status
   */
-static rt_size_t rt_sdcard_write(rt_device_t dev, rt_off_t sector, const void *buffer, rt_size_t count)
+static rt_ssize_t rt_sdcard_write(rt_device_t dev, rt_off_t sector, const void *buffer, rt_size_t count)
 {
     RT_ASSERT(dev != RT_NULL);
     struct stm32_sd *sd = (struct stm32_sd *)dev;
diff --git a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_spdifrx.c b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_spdifrx.c
index 7d0e665f64..06dfa1af24 100644
--- a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_spdifrx.c
+++ b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_spdifrx.c
@@ -134,7 +134,7 @@ static rt_err_t _close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t _read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t _read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_uint32_t tickstart = 0;
 
@@ -167,7 +167,7 @@ static rt_size_t _read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t si
     return size;
 }
 
-static rt_size_t _write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t _write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
 
diff --git a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_wm8994.c b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_wm8994.c
index cea18205fd..cdce4ac05e 100644
--- a/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_wm8994.c
+++ b/bsp/stm32/stm32mp157a-st-ev1/board/ports/drv_wm8994.c
@@ -697,14 +697,14 @@ static rt_err_t rt_wm8994_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_wm8994_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_wm8994_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
 
     return RT_EOK;
 }
 
-static rt_size_t rt_wm8994_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_wm8994_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
 
diff --git a/bsp/stm32/stm32mp157a-st-ev1/board/ports/eth/drv_eth.c b/bsp/stm32/stm32mp157a-st-ev1/board/ports/eth/drv_eth.c
index 6a29942e5b..613376d14c 100644
--- a/bsp/stm32/stm32mp157a-st-ev1/board/ports/eth/drv_eth.c
+++ b/bsp/stm32/stm32mp157a-st-ev1/board/ports/eth/drv_eth.c
@@ -494,14 +494,14 @@ static rt_err_t rt_stm32_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_stm32_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_stm32_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     LOG_D("emac read");
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_stm32_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_stm32_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     LOG_D("emac write");
     rt_set_errno(-RT_ENOSYS);
diff --git a/bsp/synwit/swm320/drivers/drv_nor_flash.c b/bsp/synwit/swm320/drivers/drv_nor_flash.c
index 5f1b0c31c7..36e747d86d 100644
--- a/bsp/synwit/swm320/drivers/drv_nor_flash.c
+++ b/bsp/synwit/swm320/drivers/drv_nor_flash.c
@@ -30,7 +30,7 @@ static long swm_norflash_read_id(struct rt_mtd_nor_device *device)
     return 0xdeadbeef;
 }
 
-static rt_size_t swm_norflash_read(struct rt_mtd_nor_device *device,
+static rt_ssize_t swm_norflash_read(struct rt_mtd_nor_device *device,
                                    rt_off_t position,
                                    rt_uint8_t *data,
                                    rt_uint32_t size)
@@ -41,7 +41,7 @@ static rt_size_t swm_norflash_read(struct rt_mtd_nor_device *device,
     return size;
 }
 
-static rt_size_t swm_norflash_write(struct rt_mtd_nor_device *device,
+static rt_ssize_t swm_norflash_write(struct rt_mtd_nor_device *device,
                                     rt_off_t position,
                                     const rt_uint8_t *data,
                                     rt_uint32_t size)
diff --git a/bsp/tm4c123bsp/libraries/Drivers/drv_uart.c b/bsp/tm4c123bsp/libraries/Drivers/drv_uart.c
index 41b133fd6e..32d2fae866 100644
--- a/bsp/tm4c123bsp/libraries/Drivers/drv_uart.c
+++ b/bsp/tm4c123bsp/libraries/Drivers/drv_uart.c
@@ -142,7 +142,7 @@ static int tm4c123_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t tm4c123_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t tm4c123_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     /* this is an interface for uart dma, reserved for uptate. */
     return 0;
diff --git a/bsp/tm4c129x/drivers/drv_eth.c b/bsp/tm4c129x/drivers/drv_eth.c
index 11b96a10a5..84523a7271 100644
--- a/bsp/tm4c129x/drivers/drv_eth.c
+++ b/bsp/tm4c129x/drivers/drv_eth.c
@@ -1425,14 +1425,14 @@ static rt_err_t eth_dev_close(rt_device_t dev)
 }
 
 /* Read */
-static rt_size_t eth_dev_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t eth_dev_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
 /* Write */
-static rt_size_t eth_dev_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t eth_dev_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/upd70f3454/drivers/uart.c b/bsp/upd70f3454/drivers/uart.c
index d452092497..ba465cfbd3 100644
--- a/bsp/upd70f3454/drivers/uart.c
+++ b/bsp/upd70f3454/drivers/uart.c
@@ -124,7 +124,7 @@ static rt_err_t rt_uart_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_uart_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_uint8_t *ptr;
     struct rt_uart_v850 *uart = (struct rt_uart_v850 *)dev;
@@ -171,7 +171,7 @@ static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_si
     return 0;
 }
 
-static rt_size_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     char *ptr;
     ptr = (char*)buffer;
diff --git a/bsp/w60x/drivers/drv_i2c.c b/bsp/w60x/drivers/drv_i2c.c
index 29632bc815..ed137c73c5 100644
--- a/bsp/w60x/drivers/drv_i2c.c
+++ b/bsp/w60x/drivers/drv_i2c.c
@@ -30,10 +30,10 @@ struct wm_i2c_bus
 
 static struct wm_i2c_bus wm_i2c;
 
-static rt_size_t wm_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t wm_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num);
-static rt_size_t wm_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t wm_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num);
 static rt_err_t wm_i2c_bus_control(struct rt_i2c_bus_device *bus,
@@ -75,7 +75,7 @@ static rt_err_t wm_i2c_send_address(struct rt_i2c_bus_device *bus,
     return RT_EOK;
 }
 
-static rt_size_t wm_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t wm_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num)
 {
@@ -125,7 +125,7 @@ static rt_size_t wm_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
 
     return i;
 }
-static rt_size_t wm_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t wm_i2c_slv_xfer(struct rt_i2c_bus_device *bus,
                                  struct rt_i2c_msg msgs[],
                                  rt_uint32_t num)
 {
diff --git a/bsp/w60x/drivers/drv_rtc.c b/bsp/w60x/drivers/drv_rtc.c
index 552f4fb46f..500201b68d 100644
--- a/bsp/w60x/drivers/drv_rtc.c
+++ b/bsp/w60x/drivers/drv_rtc.c
@@ -159,13 +159,13 @@ static rt_err_t wm_rtc_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t wm_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t wm_rtc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     wm_rtc_control(dev, RT_DEVICE_CTRL_RTC_GET_TIME, buffer);
     return size;
 }
 
-static rt_size_t wm_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t wm_rtc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     wm_rtc_control(dev, RT_DEVICE_CTRL_RTC_SET_TIME, (void *)buffer);
     return size;
diff --git a/bsp/w60x/drivers/drv_uart.c b/bsp/w60x/drivers/drv_uart.c
index e2c0f0d192..d1d2a10181 100644
--- a/bsp/w60x/drivers/drv_uart.c
+++ b/bsp/w60x/drivers/drv_uart.c
@@ -228,7 +228,7 @@ static rt_err_t  drv_uart_configure(struct rt_serial_device *serial, struct seri
 static rt_err_t  drv_uart_control(struct rt_serial_device *serial, int cmd, void *arg);
 static int       drv_uart_putc(struct rt_serial_device *serial, char c);
 static int       drv_uart_getc(struct rt_serial_device *serial);
-static rt_size_t drv_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+static rt_ssize_t drv_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
 
 const struct rt_uart_ops _uart_ops =
 {
@@ -390,7 +390,7 @@ static int drv_uart_getc(struct rt_serial_device *serial)
     return ch;
 }
 
-static rt_size_t drv_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t drv_uart_dma_transmit(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     return (0);
 }
diff --git a/bsp/wch/arm/Libraries/ch32_drivers/drv_hwi2c_ch32f10x.c b/bsp/wch/arm/Libraries/ch32_drivers/drv_hwi2c_ch32f10x.c
index e4118dff92..23ee2be882 100644
--- a/bsp/wch/arm/Libraries/ch32_drivers/drv_hwi2c_ch32f10x.c
+++ b/bsp/wch/arm/Libraries/ch32_drivers/drv_hwi2c_ch32f10x.c
@@ -291,7 +291,7 @@ static int ch32f1_i2c_write(I2C_TypeDef *i2c_periph,
     return 0;
 }
 
-static rt_size_t ch32f1_master_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t ch32f1_master_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
     struct i2c_bus_device *i2c_bus_dev;
diff --git a/bsp/wch/arm/Libraries/ch32_drivers/drv_hwi2c_ch32f20x.c b/bsp/wch/arm/Libraries/ch32_drivers/drv_hwi2c_ch32f20x.c
index 5e0236c47d..17a398907d 100644
--- a/bsp/wch/arm/Libraries/ch32_drivers/drv_hwi2c_ch32f20x.c
+++ b/bsp/wch/arm/Libraries/ch32_drivers/drv_hwi2c_ch32f20x.c
@@ -291,7 +291,7 @@ static int ch32f2_i2c_write(I2C_TypeDef *i2c_periph,
     return 0;
 }
 
-static rt_size_t ch32f2_master_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
+static rt_ssize_t ch32f2_master_xfer(struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
 {
     struct rt_i2c_msg *msg;
     struct i2c_bus_device *i2c_bus_dev;
diff --git a/bsp/wch/arm/ch579m/board/drv_eth.c b/bsp/wch/arm/ch579m/board/drv_eth.c
index 176c6c2fbf..bdbeff06bb 100644
--- a/bsp/wch/arm/ch579m/board/drv_eth.c
+++ b/bsp/wch/arm/ch579m/board/drv_eth.c
@@ -42,13 +42,13 @@ static rt_err_t eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/bsp/wch/risc-v/Libraries/ch56x_drivers/ch56x_usbd.c b/bsp/wch/risc-v/Libraries/ch56x_drivers/ch56x_usbd.c
index 44ac67f475..512c190616 100644
--- a/bsp/wch/risc-v/Libraries/ch56x_drivers/ch56x_usbd.c
+++ b/bsp/wch/risc-v/Libraries/ch56x_drivers/ch56x_usbd.c
@@ -159,7 +159,7 @@ static rt_err_t udc_ep_disable(struct uendpoint *ep)
     return RT_EOK;
 }
 
-static rt_size_t udc_ep_read_prepare(uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t udc_ep_read_prepare(uint8_t address, void *buffer, rt_size_t size)
 {
     volatile struct usbhs_registers *usbhs = (void *)USBHS_REG_BASE;
 
@@ -206,7 +206,7 @@ static rt_size_t udc_ep_read_prepare(uint8_t address, void *buffer, rt_size_t si
     return size;
 }
 
-static rt_size_t udc_ep_read(uint8_t address, void *buffer)
+static rt_ssize_t udc_ep_read(uint8_t address, void *buffer)
 {
     volatile struct usbhs_registers *usbhs = (void *)USBHS_REG_BASE;
 
@@ -236,7 +236,7 @@ static rt_size_t udc_ep_read(uint8_t address, void *buffer)
     return size;
 }
 
-static rt_size_t udc_ep_write(uint8_t address, void *buffer, rt_size_t size)
+static rt_ssize_t udc_ep_write(uint8_t address, void *buffer, rt_size_t size)
 {
     volatile struct usbhs_registers *usbhs = (void *)USBHS_REG_BASE;
 
diff --git a/bsp/x86/drivers/console.c b/bsp/x86/drivers/console.c
index 4fe1daeeed..f6dd8734bb 100644
--- a/bsp/x86/drivers/console.c
+++ b/bsp/x86/drivers/console.c
@@ -155,7 +155,7 @@ static rt_err_t rt_console_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t rt_console_write(rt_device_t dev, rt_off_t pos, const void * buffer, rt_size_t size)
+static rt_ssize_t rt_console_write(rt_device_t dev, rt_off_t pos, const void * buffer, rt_size_t size)
 {
     rt_size_t i = size;
     const char* str = buffer;
@@ -168,7 +168,7 @@ static rt_size_t rt_console_write(rt_device_t dev, rt_off_t pos, const void * bu
     return size;
 }
 
-static rt_size_t rt_console_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_console_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr = buffer;
     rt_err_t err_code = RT_EOK;
diff --git a/bsp/x86/drivers/floppy.c b/bsp/x86/drivers/floppy.c
index 077ce40e4d..7f3837fcfd 100644
--- a/bsp/x86/drivers/floppy.c
+++ b/bsp/x86/drivers/floppy.c
@@ -264,7 +264,7 @@ static rt_err_t rt_floppy_close(rt_device_t dev)
  * buffer:
  * size  : how many blocks
  */
-static rt_size_t rt_floppy_read(rt_device_t device, rt_off_t position, void *buffer, rt_size_t size)
+static rt_ssize_t rt_floppy_read(rt_device_t device, rt_off_t position, void *buffer, rt_size_t size)
 {
     rt_size_t doSize = size;
 
@@ -300,7 +300,7 @@ static rt_size_t rt_floppy_read(rt_device_t device, rt_off_t position, void *buf
  * buffer:
  * size  : how many blocks
  */
-static rt_size_t rt_floppy_write(rt_device_t device, rt_off_t position, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_floppy_write(rt_device_t device, rt_off_t position, const void *buffer, rt_size_t size)
 {
     rt_mutex_take(&lock, RT_WAITING_FOREVER);
     panic("FIXME:I don't know how!\n");
diff --git a/bsp/xplorer4330/drivers/drv_led.c b/bsp/xplorer4330/drivers/drv_led.c
index 48cbd089b0..b97d32c6b3 100644
--- a/bsp/xplorer4330/drivers/drv_led.c
+++ b/bsp/xplorer4330/drivers/drv_led.c
@@ -69,7 +69,7 @@ static rt_err_t rt_led_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
+static rt_ssize_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
                              rt_size_t size)
 {
     rt_ubase_t index = 0;
@@ -94,7 +94,7 @@ static rt_size_t rt_led_read(rt_device_t dev, rt_off_t pos, void *buffer,
     return index;
 }
 
-static rt_size_t rt_led_write(rt_device_t dev, rt_off_t pos,
+static rt_ssize_t rt_led_write(rt_device_t dev, rt_off_t pos,
                               const void *buffer, rt_size_t size)
 {
     rt_ubase_t index = 0;
diff --git a/bsp/zynqmp-r5-axu4ev/drivers/drv_eth.c b/bsp/zynqmp-r5-axu4ev/drivers/drv_eth.c
index b7b9a22a1d..9bcf708593 100644
--- a/bsp/zynqmp-r5-axu4ev/drivers/drv_eth.c
+++ b/bsp/zynqmp-r5-axu4ev/drivers/drv_eth.c
@@ -216,14 +216,14 @@ static rt_err_t rt_zynqmp_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_zynqmp_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_zynqmp_eth_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     LOG_D("emac read");
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_zynqmp_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_zynqmp_eth_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     LOG_D("emac write");
     rt_set_errno(-RT_ENOSYS);
diff --git a/bsp/zynqmp-r5-axu4ev/drivers/drv_sdcard.c b/bsp/zynqmp-r5-axu4ev/drivers/drv_sdcard.c
index 155b7da552..3ce161b0d4 100644
--- a/bsp/zynqmp-r5-axu4ev/drivers/drv_sdcard.c
+++ b/bsp/zynqmp-r5-axu4ev/drivers/drv_sdcard.c
@@ -359,7 +359,7 @@ static rt_err_t rt_sdcard_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     RT_ASSERT(((rt_uint32_t)buffer % 4) == 0);
     DRESULT status;
@@ -376,7 +376,7 @@ static rt_size_t rt_sdcard_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_
     return 0;
 }
 
-static rt_size_t rt_sdcard_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_sdcard_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     RT_ASSERT(((rt_uint32_t)buffer % 4) == 0);
     DRESULT status;
diff --git a/components/drivers/audio/audio.c b/components/drivers/audio/audio.c
index edef7d0eeb..2907b10ba0 100644
--- a/components/drivers/audio/audio.c
+++ b/components/drivers/audio/audio.c
@@ -357,7 +357,7 @@ static rt_err_t _audio_dev_close(struct rt_device *dev)
     return RT_EOK;
 }
 
-static rt_size_t _audio_dev_read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t _audio_dev_read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     struct rt_audio_device *audio;
     RT_ASSERT(dev != RT_NULL);
@@ -369,7 +369,7 @@ static rt_size_t _audio_dev_read(struct rt_device *dev, rt_off_t pos, void *buff
     return rt_device_read(RT_DEVICE(&audio->record->pipe), pos, buffer, size);
 }
 
-static rt_size_t _audio_dev_write(struct rt_device *dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t _audio_dev_write(struct rt_device *dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
 
     struct rt_audio_device *audio;
diff --git a/components/drivers/audio/audio_pipe.c b/components/drivers/audio/audio_pipe.c
index 35a3faf73f..4c8aa288b1 100644
--- a/components/drivers/audio/audio_pipe.c
+++ b/components/drivers/audio/audio_pipe.c
@@ -32,7 +32,7 @@ static void _rt_pipe_resume_writer(struct rt_audio_pipe *pipe)
     }
 }
 
-static rt_size_t rt_pipe_read(rt_device_t dev,
+static rt_ssize_t rt_pipe_read(rt_device_t dev,
                               rt_off_t    pos,
                               void       *buffer,
                               rt_size_t   size)
@@ -114,7 +114,7 @@ static void _rt_pipe_resume_reader(struct rt_audio_pipe *pipe)
     }
 }
 
-static rt_size_t rt_pipe_write(rt_device_t dev,
+static rt_ssize_t rt_pipe_write(rt_device_t dev,
                                rt_off_t    pos,
                                const void *buffer,
                                rt_size_t   size)
diff --git a/components/drivers/can/can.c b/components/drivers/can/can.c
index a3d81f6081..53bc2ba45a 100644
--- a/components/drivers/can/can.c
+++ b/components/drivers/can/can.c
@@ -438,7 +438,7 @@ static rt_err_t rt_can_close(struct rt_device *dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_can_read(struct rt_device *dev,
+static rt_ssize_t rt_can_read(struct rt_device *dev,
                              rt_off_t          pos,
                              void             *buffer,
                              rt_size_t         size)
@@ -458,7 +458,7 @@ static rt_size_t rt_can_read(struct rt_device *dev,
     return 0;
 }
 
-static rt_size_t rt_can_write(struct rt_device *dev,
+static rt_ssize_t rt_can_write(struct rt_device *dev,
                               rt_off_t          pos,
                               const void       *buffer,
                               rt_size_t         size)
diff --git a/components/drivers/hwtimer/hwtimer.c b/components/drivers/hwtimer/hwtimer.c
index 189ef7df49..f8e1a35275 100644
--- a/components/drivers/hwtimer/hwtimer.c
+++ b/components/drivers/hwtimer/hwtimer.c
@@ -143,7 +143,7 @@ static rt_err_t rt_hwtimer_close(struct rt_device *dev)
     return result;
 }
 
-static rt_size_t rt_hwtimer_read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_hwtimer_read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_hwtimer_t *timer;
     rt_hwtimerval_t tv;
@@ -175,7 +175,7 @@ static rt_size_t rt_hwtimer_read(struct rt_device *dev, rt_off_t pos, void *buff
     return size;
 }
 
-static rt_size_t rt_hwtimer_write(struct rt_device *dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_hwtimer_write(struct rt_device *dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_base_t level;
     rt_uint32_t t;
diff --git a/components/drivers/i2c/i2c-bit-ops.c b/components/drivers/i2c/i2c-bit-ops.c
index ee6acd886d..5446184558 100644
--- a/components/drivers/i2c/i2c-bit-ops.c
+++ b/components/drivers/i2c/i2c-bit-ops.c
@@ -186,7 +186,7 @@ static rt_int32_t i2c_readb(struct rt_i2c_bus_device *bus)
     return data;
 }
 
-static rt_size_t i2c_send_bytes(struct rt_i2c_bus_device *bus,
+static rt_ssize_t i2c_send_bytes(struct rt_i2c_bus_device *bus,
                                 struct rt_i2c_msg        *msg)
 {
     rt_int32_t ret;
@@ -240,7 +240,7 @@ static rt_err_t i2c_send_ack_or_nack(struct rt_i2c_bus_device *bus, int ack)
     return RT_EOK;
 }
 
-static rt_size_t i2c_recv_bytes(struct rt_i2c_bus_device *bus,
+static rt_ssize_t i2c_recv_bytes(struct rt_i2c_bus_device *bus,
                                 struct rt_i2c_msg        *msg)
 {
     rt_int32_t val;
@@ -366,7 +366,7 @@ static rt_err_t i2c_bit_send_address(struct rt_i2c_bus_device *bus,
     return RT_EOK;
 }
 
-static rt_size_t i2c_bit_xfer(struct rt_i2c_bus_device *bus,
+static rt_ssize_t i2c_bit_xfer(struct rt_i2c_bus_device *bus,
                               struct rt_i2c_msg         msgs[],
                               rt_uint32_t               num)
 {
diff --git a/components/drivers/i2c/i2c_dev.c b/components/drivers/i2c/i2c_dev.c
index 4e2ca8924f..ffd24f95b5 100644
--- a/components/drivers/i2c/i2c_dev.c
+++ b/components/drivers/i2c/i2c_dev.c
@@ -20,7 +20,7 @@
 #endif
 #include <rtdbg.h>
 
-static rt_size_t i2c_bus_device_read(rt_device_t dev,
+static rt_ssize_t i2c_bus_device_read(rt_device_t dev,
                                      rt_off_t    pos,
                                      void       *buffer,
                                      rt_size_t   count)
@@ -40,7 +40,7 @@ static rt_size_t i2c_bus_device_read(rt_device_t dev,
     return rt_i2c_master_recv(bus, addr, flags, (rt_uint8_t *)buffer, count);
 }
 
-static rt_size_t i2c_bus_device_write(rt_device_t dev,
+static rt_ssize_t i2c_bus_device_write(rt_device_t dev,
                                       rt_off_t    pos,
                                       const void *buffer,
                                       rt_size_t   count)
diff --git a/components/drivers/include/drivers/audio.h b/components/drivers/include/drivers/audio.h
index d9a7388678..79856a37a8 100644
--- a/components/drivers/include/drivers/audio.h
+++ b/components/drivers/include/drivers/audio.h
@@ -105,7 +105,7 @@ struct rt_audio_ops
     rt_err_t (*init)(struct rt_audio_device *audio);
     rt_err_t (*start)(struct rt_audio_device *audio, int stream);
     rt_err_t (*stop)(struct rt_audio_device *audio, int stream);
-    rt_size_t (*transmit)(struct rt_audio_device *audio, const void *writeBuf, void *readBuf, rt_size_t size);
+    rt_ssize_t (*transmit)(struct rt_audio_device *audio, const void *writeBuf, void *readBuf, rt_size_t size);
     /* get page size of codec or private buffer's info */
     void (*buffer_info)(struct rt_audio_device *audio, struct rt_audio_buf_info *info);
 };
diff --git a/components/drivers/include/drivers/i2c.h b/components/drivers/include/drivers/i2c.h
index 308c344294..3186f13414 100644
--- a/components/drivers/include/drivers/i2c.h
+++ b/components/drivers/include/drivers/i2c.h
@@ -38,10 +38,10 @@ struct rt_i2c_bus_device;
 
 struct rt_i2c_bus_device_ops
 {
-    rt_size_t (*master_xfer)(struct rt_i2c_bus_device *bus,
+    rt_ssize_t (*master_xfer)(struct rt_i2c_bus_device *bus,
                              struct rt_i2c_msg msgs[],
                              rt_uint32_t num);
-    rt_size_t (*slave_xfer)(struct rt_i2c_bus_device *bus,
+    rt_ssize_t (*slave_xfer)(struct rt_i2c_bus_device *bus,
                             struct rt_i2c_msg msgs[],
                             rt_uint32_t num);
     rt_err_t (*i2c_bus_control)(struct rt_i2c_bus_device *bus,
diff --git a/components/drivers/include/drivers/serial.h b/components/drivers/include/drivers/serial.h
index b4c6fb4a7a..e7432b1e1d 100644
--- a/components/drivers/include/drivers/serial.h
+++ b/components/drivers/include/drivers/serial.h
@@ -167,7 +167,7 @@ struct rt_uart_ops
     int (*putc)(struct rt_serial_device *serial, char c);
     int (*getc)(struct rt_serial_device *serial);
 
-    rt_size_t (*dma_transmit)(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
+    rt_ssize_t (*dma_transmit)(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
 };
 
 void rt_hw_serial_isr(struct rt_serial_device *serial, int event);
diff --git a/components/drivers/ipc/pipe.c b/components/drivers/ipc/pipe.c
index 7567a73482..ccb953bc23 100644
--- a/components/drivers/ipc/pipe.c
+++ b/components/drivers/ipc/pipe.c
@@ -462,7 +462,7 @@ rt_err_t rt_pipe_close(rt_device_t device)
  * @return   Return the length of data read.
  *           When the return value is 0, it means the pipe device handle is empty or the count is 0.
  */
-rt_size_t rt_pipe_read(rt_device_t device, rt_off_t pos, void *buffer, rt_size_t count)
+rt_ssize_t rt_pipe_read(rt_device_t device, rt_off_t pos, void *buffer, rt_size_t count)
 {
     uint8_t *pbuf;
     rt_size_t read_bytes = 0;
@@ -510,7 +510,7 @@ rt_size_t rt_pipe_read(rt_device_t device, rt_off_t pos, void *buffer, rt_size_t
  * @return   Return the length of data written.
  *           When the return value is 0, it means the pipe device handle is empty or the count is 0.
  */
-rt_size_t rt_pipe_write(rt_device_t device, rt_off_t pos, const void *buffer, rt_size_t count)
+rt_ssize_t rt_pipe_write(rt_device_t device, rt_off_t pos, const void *buffer, rt_size_t count)
 {
     uint8_t *pbuf;
     rt_size_t write_bytes = 0;
diff --git a/components/drivers/misc/adc.c b/components/drivers/misc/adc.c
index a85be09fe9..29dbb86f96 100644
--- a/components/drivers/misc/adc.c
+++ b/components/drivers/misc/adc.c
@@ -20,7 +20,7 @@
 #define DBG_LVL DBG_INFO
 #include <rtdbg.h>
 
-static rt_size_t _adc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t _adc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_err_t result = RT_EOK;
     rt_size_t i;
diff --git a/components/drivers/misc/dac.c b/components/drivers/misc/dac.c
index c1176cc36c..788eac851b 100644
--- a/components/drivers/misc/dac.c
+++ b/components/drivers/misc/dac.c
@@ -17,7 +17,7 @@
 #define DBG_LVL DBG_INFO
 #include <rtdbg.h>
 
-static rt_size_t _dac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t _dac_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_err_t result = RT_EOK;
     rt_size_t i;
diff --git a/components/drivers/misc/pin.c b/components/drivers/misc/pin.c
index 91913dccfd..a5a5addafe 100644
--- a/components/drivers/misc/pin.c
+++ b/components/drivers/misc/pin.c
@@ -13,7 +13,7 @@
 #include <drivers/pin.h>
 
 static struct rt_device_pin _hw_pin;
-static rt_size_t _pin_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t _pin_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     struct rt_device_pin_status *status;
     struct rt_device_pin *pin = (struct rt_device_pin *)dev;
@@ -29,7 +29,7 @@ static rt_size_t _pin_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_
     return size;
 }
 
-static rt_size_t _pin_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t _pin_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     struct rt_device_pin_status *status;
     struct rt_device_pin *pin = (struct rt_device_pin *)dev;
diff --git a/components/drivers/misc/pulse_encoder.c b/components/drivers/misc/pulse_encoder.c
index d5efcef8e7..39bf3de2f3 100644
--- a/components/drivers/misc/pulse_encoder.c
+++ b/components/drivers/misc/pulse_encoder.c
@@ -55,7 +55,7 @@ static rt_err_t rt_pulse_encoder_close(struct rt_device *dev)
     }
 }
 
-static rt_size_t rt_pulse_encoder_read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_pulse_encoder_read(struct rt_device *dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     struct rt_pulse_encoder_device *pulse_encoder;
 
diff --git a/components/drivers/misc/rt_drv_pwm.c b/components/drivers/misc/rt_drv_pwm.c
index 7cc01e4e1a..25b45f9d43 100644
--- a/components/drivers/misc/rt_drv_pwm.c
+++ b/components/drivers/misc/rt_drv_pwm.c
@@ -43,7 +43,7 @@ pos: channel
 void *buffer: rt_uint32_t pulse[size]
 size : number of pulse, only set to sizeof(rt_uint32_t).
 */
-static rt_size_t _pwm_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t _pwm_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_err_t result = RT_EOK;
     struct rt_device_pwm *pwm = (struct rt_device_pwm *)dev;
@@ -71,7 +71,7 @@ pos: channel
 void *buffer: rt_uint32_t pulse[size]
 size : number of pulse, only set to sizeof(rt_uint32_t).
 */
-static rt_size_t _pwm_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t _pwm_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_err_t result = RT_EOK;
     struct rt_device_pwm *pwm = (struct rt_device_pwm *)dev;
diff --git a/components/drivers/misc/rt_inputcapture.c b/components/drivers/misc/rt_inputcapture.c
index c7a9edaaf6..067aeef2df 100644
--- a/components/drivers/misc/rt_inputcapture.c
+++ b/components/drivers/misc/rt_inputcapture.c
@@ -81,7 +81,7 @@ static rt_err_t rt_inputcapture_close(struct rt_device *dev)
     return ret;
 }
 
-static rt_size_t rt_inputcapture_read(struct rt_device *dev,
+static rt_ssize_t rt_inputcapture_read(struct rt_device *dev,
                                  rt_off_t          pos,
                                  void             *buffer,
                                  rt_size_t         size)
diff --git a/components/drivers/misc/rt_null.c b/components/drivers/misc/rt_null.c
index 3e4cf6f3da..bc329ab50e 100644
--- a/components/drivers/misc/rt_null.c
+++ b/components/drivers/misc/rt_null.c
@@ -12,12 +12,12 @@
 
 static struct rt_device null_dev;
 
-static rt_size_t null_read    (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t null_read    (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     return 0;
 }
 
-static rt_size_t null_write   (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t null_write   (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     return size;
 }
diff --git a/components/drivers/misc/rt_random.c b/components/drivers/misc/rt_random.c
index 1ea0480b7c..9b52918ae9 100644
--- a/components/drivers/misc/rt_random.c
+++ b/components/drivers/misc/rt_random.c
@@ -19,7 +19,7 @@ static rt_uint16_t calc_random(void)
     return (seed >> 16) & 0x7FFF;   /* return bits 16~30 */
 }
 
-static rt_size_t random_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t random_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_uint16_t rand = calc_random();
     ssize_t ret = sizeof(rand);
@@ -27,7 +27,7 @@ static rt_size_t random_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_siz
     return ret;
 }
 
-static rt_size_t random_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t random_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     ssize_t ret = sizeof(seed);
     rt_memcpy(&seed, buffer, ret);
@@ -93,7 +93,7 @@ static rt_uint16_t calc_urandom(void)
     return (useed >> 16) & 0x7FFF;   /* return bits 16~30 */
 }
 
-static rt_size_t random_uread(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t random_uread(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_uint16_t rand = calc_urandom();
     ssize_t ret = sizeof(rand);
@@ -101,7 +101,7 @@ static rt_size_t random_uread(rt_device_t dev, rt_off_t pos, void *buffer, rt_si
     return ret;
 }
 
-static rt_size_t random_uwrite(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t random_uwrite(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     ssize_t ret = sizeof(useed);
     rt_memcpy(&useed, buffer, ret);
diff --git a/components/drivers/misc/rt_zero.c b/components/drivers/misc/rt_zero.c
index f2657a2360..08df5cb3aa 100644
--- a/components/drivers/misc/rt_zero.c
+++ b/components/drivers/misc/rt_zero.c
@@ -12,13 +12,13 @@
 
 static struct rt_device zero_dev;
 
-static rt_size_t zero_read    (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t zero_read    (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_memset(buffer, 0, size);
     return size;
 }
 
-static rt_size_t zero_write   (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t zero_write   (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     return size;
 }
diff --git a/components/drivers/mtd/mtd_nand.c b/components/drivers/mtd/mtd_nand.c
index 6ca56f9a6d..9c3397dfdd 100644
--- a/components/drivers/mtd/mtd_nand.c
+++ b/components/drivers/mtd/mtd_nand.c
@@ -34,7 +34,7 @@ static rt_err_t _mtd_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t _mtd_read(rt_device_t dev,
+static rt_ssize_t _mtd_read(rt_device_t dev,
                            rt_off_t    pos,
                            void       *buffer,
                            rt_size_t   size)
@@ -42,7 +42,7 @@ static rt_size_t _mtd_read(rt_device_t dev,
     return size;
 }
 
-static rt_size_t _mtd_write(rt_device_t dev,
+static rt_ssize_t _mtd_write(rt_device_t dev,
                             rt_off_t    pos,
                             const void *buffer,
                             rt_size_t   size)
diff --git a/components/drivers/mtd/mtd_nor.c b/components/drivers/mtd/mtd_nor.c
index af3b50e42f..6824190475 100644
--- a/components/drivers/mtd/mtd_nor.c
+++ b/components/drivers/mtd/mtd_nor.c
@@ -30,7 +30,7 @@ static rt_err_t _mtd_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t _mtd_read(rt_device_t dev,
+static rt_ssize_t _mtd_read(rt_device_t dev,
                            rt_off_t    pos,
                            void       *buffer,
                            rt_size_t   size)
@@ -38,7 +38,7 @@ static rt_size_t _mtd_read(rt_device_t dev,
     return size;
 }
 
-static rt_size_t _mtd_write(rt_device_t dev,
+static rt_ssize_t _mtd_write(rt_device_t dev,
                             rt_off_t    pos,
                             const void *buffer,
                             rt_size_t   size)
diff --git a/components/drivers/phy/phy.c b/components/drivers/phy/phy.c
index ef47a91d7c..317b24ebfc 100644
--- a/components/drivers/phy/phy.c
+++ b/components/drivers/phy/phy.c
@@ -18,13 +18,13 @@
 #include <rtdbg.h>
 
 
-static rt_size_t phy_device_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t count)
+static rt_ssize_t phy_device_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t count)
 {
     struct rt_phy_device *phy = (struct rt_phy_device *)dev->user_data;
     struct rt_phy_msg *msg = (struct rt_phy_msg *)buffer;
     return phy->bus->ops->read(phy->bus, phy->addr, msg->reg, &(msg->value), 4);
 }
-static rt_size_t phy_device_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t count)
+static rt_ssize_t phy_device_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t count)
 {
     struct rt_phy_device *phy = (struct rt_phy_device *)dev->user_data;
     struct rt_phy_msg *msg = (struct rt_phy_msg *)buffer;
diff --git a/components/drivers/pm/pm.c b/components/drivers/pm/pm.c
index 0c6dcf065d..f70333090c 100644
--- a/components/drivers/pm/pm.c
+++ b/components/drivers/pm/pm.c
@@ -845,7 +845,7 @@ void rt_pm_default_set(rt_uint8_t sleep_mode)
 /**
  * RT-Thread device interface for PM device
  */
-static rt_size_t _rt_pm_device_read(rt_device_t dev,
+static rt_ssize_t _rt_pm_device_read(rt_device_t dev,
                                     rt_off_t    pos,
                                     void       *buffer,
                                     rt_size_t   size)
@@ -868,7 +868,7 @@ static rt_size_t _rt_pm_device_read(rt_device_t dev,
     return length;
 }
 
-static rt_size_t _rt_pm_device_write(rt_device_t dev,
+static rt_ssize_t _rt_pm_device_write(rt_device_t dev,
                                      rt_off_t    pos,
                                      const void *buffer,
                                      rt_size_t   size)
diff --git a/components/drivers/sdio/block_dev.c b/components/drivers/sdio/block_dev.c
index 59eb56cdcd..0025e7f08a 100644
--- a/components/drivers/sdio/block_dev.c
+++ b/components/drivers/sdio/block_dev.c
@@ -280,7 +280,7 @@ static rt_err_t rt_mmcsd_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t rt_mmcsd_read(rt_device_t dev,
+static rt_ssize_t rt_mmcsd_read(rt_device_t dev,
                                rt_off_t    pos,
                                void       *buffer,
                                rt_size_t   size)
@@ -321,7 +321,7 @@ static rt_size_t rt_mmcsd_read(rt_device_t dev,
     return size - remain_size;
 }
 
-static rt_size_t rt_mmcsd_write(rt_device_t dev,
+static rt_ssize_t rt_mmcsd_write(rt_device_t dev,
                                 rt_off_t    pos,
                                 const void *buffer,
                                 rt_size_t   size)
diff --git a/components/drivers/sensor/sensor.c b/components/drivers/sensor/sensor.c
index 40e4b46037..8835c10bac 100644
--- a/components/drivers/sensor/sensor.c
+++ b/components/drivers/sensor/sensor.c
@@ -284,7 +284,7 @@ __exit:
     return RT_EOK;
 }
 
-static rt_size_t _sensor_read(rt_device_t dev, rt_off_t pos, void *buf, rt_size_t len)
+static rt_ssize_t _sensor_read(rt_device_t dev, rt_off_t pos, void *buf, rt_size_t len)
 {
     rt_sensor_t sensor = (rt_sensor_t)dev;
     rt_size_t result = 0;
diff --git a/components/drivers/serial/serial.c b/components/drivers/serial/serial.c
index d667d70efd..06b519166c 100644
--- a/components/drivers/serial/serial.c
+++ b/components/drivers/serial/serial.c
@@ -381,7 +381,7 @@ static void _serial_check_buffer_size(void)
 }
 
 #if defined(RT_USING_POSIX_STDIO) || defined(RT_SERIAL_USING_DMA)
-static rt_size_t _serial_fifo_calc_recved_len(struct rt_serial_device *serial)
+static rt_ssize_t _serial_fifo_calc_recved_len(struct rt_serial_device *serial)
 {
     struct rt_serial_rx_fifo *rx_fifo = (struct rt_serial_rx_fifo *) serial->serial_rx;
 
@@ -413,7 +413,7 @@ static rt_size_t _serial_fifo_calc_recved_len(struct rt_serial_device *serial)
  *
  * @return length
  */
-static rt_size_t rt_dma_calc_recved_len(struct rt_serial_device *serial)
+static rt_ssize_t rt_dma_calc_recved_len(struct rt_serial_device *serial)
 {
     return _serial_fifo_calc_recved_len(serial);
 }
@@ -850,7 +850,7 @@ static rt_err_t rt_serial_close(struct rt_device *dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read(struct rt_device *dev,
+static rt_ssize_t rt_serial_read(struct rt_device *dev,
                                 rt_off_t          pos,
                                 void             *buffer,
                                 rt_size_t         size)
@@ -876,7 +876,7 @@ static rt_size_t rt_serial_read(struct rt_device *dev,
     return _serial_poll_rx(serial, (rt_uint8_t *)buffer, size);
 }
 
-static rt_size_t rt_serial_write(struct rt_device *dev,
+static rt_ssize_t rt_serial_write(struct rt_device *dev,
                                  rt_off_t          pos,
                                  const void       *buffer,
                                  rt_size_t         size)
diff --git a/components/drivers/serial/serial_v2.c b/components/drivers/serial/serial_v2.c
index a6e4e22def..9e809048bd 100644
--- a/components/drivers/serial/serial_v2.c
+++ b/components/drivers/serial/serial_v2.c
@@ -194,7 +194,7 @@ const static struct dfs_file_ops _serial_fops =
 };
 #endif /* RT_USING_POSIX_STDIO */
 
-static rt_size_t rt_serial_get_linear_buffer(struct rt_ringbuffer       *rb,
+static rt_ssize_t rt_serial_get_linear_buffer(struct rt_ringbuffer       *rb,
                                                     rt_uint8_t         **ptr)
 {
     rt_size_t size;
@@ -220,7 +220,7 @@ static rt_size_t rt_serial_get_linear_buffer(struct rt_ringbuffer       *rb,
     return rb->buffer_size - rb->read_index;
 }
 
-static rt_size_t rt_serial_update_read_index(struct rt_ringbuffer    *rb,
+static rt_ssize_t rt_serial_update_read_index(struct rt_ringbuffer    *rb,
                                                     rt_uint16_t       read_index)
 {
     rt_size_t size;
@@ -253,7 +253,7 @@ static rt_size_t rt_serial_update_read_index(struct rt_ringbuffer    *rb,
     return read_index;
 }
 
-static rt_size_t rt_serial_update_write_index(struct rt_ringbuffer  *rb,
+static rt_ssize_t rt_serial_update_write_index(struct rt_ringbuffer  *rb,
                                                      rt_uint16_t     write_size)
 {
     rt_uint16_t size;
@@ -386,7 +386,7 @@ rt_size_t _serial_poll_tx(struct rt_device           *dev,
   * @param size Receive data buffer length.
   * @return Return the final length of data received.
   */
-static rt_size_t _serial_fifo_rx(struct rt_device        *dev,
+static rt_ssize_t _serial_fifo_rx(struct rt_device        *dev,
                                         rt_off_t          pos,
                                         void             *buffer,
                                         rt_size_t         size)
@@ -448,7 +448,7 @@ static rt_size_t _serial_fifo_rx(struct rt_device        *dev,
   * @param size Transmit data buffer length.
   * @return Return the final length of data transmit.
   */
-static rt_size_t _serial_fifo_tx_blocking_nbuf(struct rt_device        *dev,
+static rt_ssize_t _serial_fifo_tx_blocking_nbuf(struct rt_device        *dev,
                                                       rt_off_t          pos,
                                                 const void             *buffer,
                                                       rt_size_t         size)
@@ -495,7 +495,7 @@ static rt_size_t _serial_fifo_tx_blocking_nbuf(struct rt_device        *dev,
   * @param size Transmit data buffer length.
   * @return Return the final length of data transmit.
   */
-static rt_size_t _serial_fifo_tx_blocking_buf(struct rt_device        *dev,
+static rt_ssize_t _serial_fifo_tx_blocking_buf(struct rt_device        *dev,
                                                      rt_off_t          pos,
                                                const void             *buffer,
                                                     rt_size_t          size)
@@ -555,7 +555,7 @@ static rt_size_t _serial_fifo_tx_blocking_buf(struct rt_device        *dev,
   * @param size Transmit data buffer length.
   * @return Return the final length of data transmit.
   */
-static rt_size_t _serial_fifo_tx_nonblocking(struct rt_device        *dev,
+static rt_ssize_t _serial_fifo_tx_nonblocking(struct rt_device        *dev,
                                                     rt_off_t          pos,
                                               const void             *buffer,
                                                     rt_size_t         size)
@@ -1372,7 +1372,7 @@ static rt_err_t rt_serial_control(struct rt_device *dev,
 }
 
 #ifdef RT_USING_DEVICE_OPS
-static rt_size_t rt_serial_read(struct rt_device *dev,
+static rt_ssize_t rt_serial_read(struct rt_device *dev,
                                 rt_off_t          pos,
                                 void             *buffer,
                                 rt_size_t         size)
@@ -1393,7 +1393,7 @@ static rt_size_t rt_serial_read(struct rt_device *dev,
 }
 
 
-static rt_size_t rt_serial_write(struct rt_device *dev,
+static rt_ssize_t rt_serial_write(struct rt_device *dev,
                                  rt_off_t          pos,
                                  const void       *buffer,
                                  rt_size_t         size)
diff --git a/components/drivers/spi/enc28j60.c b/components/drivers/spi/enc28j60.c
index 361db776f6..f3c3ecb30b 100644
--- a/components/drivers/spi/enc28j60.c
+++ b/components/drivers/spi/enc28j60.c
@@ -381,14 +381,14 @@ static rt_err_t enc28j60_close(rt_device_t dev)
 }
 
 /* Read */
-static rt_size_t enc28j60_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t enc28j60_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return RT_EOK;
 }
 
 /* Write */
-static rt_size_t enc28j60_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t enc28j60_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/components/drivers/spi/spi_dev.c b/components/drivers/spi/spi_dev.c
index 4b21466b0d..2d63fbcfbb 100644
--- a/components/drivers/spi/spi_dev.c
+++ b/components/drivers/spi/spi_dev.c
@@ -11,7 +11,7 @@
 #include <drivers/spi.h>
 
 /* SPI bus device interface, compatible with RT-Thread 0.3.x/1.0.x */
-static rt_size_t _spi_bus_device_read(rt_device_t dev,
+static rt_ssize_t _spi_bus_device_read(rt_device_t dev,
                                       rt_off_t    pos,
                                       void       *buffer,
                                       rt_size_t   size)
@@ -25,7 +25,7 @@ static rt_size_t _spi_bus_device_read(rt_device_t dev,
     return rt_spi_transfer(bus->owner, RT_NULL, buffer, size);
 }
 
-static rt_size_t _spi_bus_device_write(rt_device_t dev,
+static rt_ssize_t _spi_bus_device_write(rt_device_t dev,
                                        rt_off_t    pos,
                                        const void *buffer,
                                        rt_size_t   size)
@@ -77,7 +77,7 @@ rt_err_t rt_spi_bus_device_init(struct rt_spi_bus *bus, const char *name)
 }
 
 /* SPI Dev device interface, compatible with RT-Thread 0.3.x/1.0.x */
-static rt_size_t _spidev_device_read(rt_device_t dev,
+static rt_ssize_t _spidev_device_read(rt_device_t dev,
                                      rt_off_t    pos,
                                      void       *buffer,
                                      rt_size_t   size)
@@ -91,7 +91,7 @@ static rt_size_t _spidev_device_read(rt_device_t dev,
     return rt_spi_transfer(device, RT_NULL, buffer, size);
 }
 
-static rt_size_t _spidev_device_write(rt_device_t dev,
+static rt_ssize_t _spidev_device_write(rt_device_t dev,
                                       rt_off_t    pos,
                                       const void *buffer,
                                       rt_size_t   size)
diff --git a/components/drivers/spi/spi_flash_sfud.c b/components/drivers/spi/spi_flash_sfud.c
index 30bc77a57d..83f8537c72 100644
--- a/components/drivers/spi/spi_flash_sfud.c
+++ b/components/drivers/spi/spi_flash_sfud.c
@@ -86,7 +86,7 @@ static rt_err_t rt_sfud_control(rt_device_t dev, int cmd, void *args) {
 }
 
 
-static rt_size_t rt_sfud_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size) {
+static rt_ssize_t rt_sfud_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size) {
     struct spi_flash_device *rtt_dev = (struct spi_flash_device *) (dev->user_data);
     sfud_flash *sfud_dev = (sfud_flash *) (rtt_dev->user_data);
 
@@ -104,7 +104,7 @@ static rt_size_t rt_sfud_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_si
     }
 }
 
-static rt_size_t rt_sfud_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size) {
+static rt_ssize_t rt_sfud_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size) {
     struct spi_flash_device *rtt_dev = (struct spi_flash_device *) (dev->user_data);
     sfud_flash *sfud_dev = (sfud_flash *) (rtt_dev->user_data);
 
diff --git a/components/drivers/spi/spi_msd.c b/components/drivers/spi/spi_msd.c
index 6bd0501694..dce2a7c8b0 100644
--- a/components/drivers/spi/spi_msd.c
+++ b/components/drivers/spi/spi_msd.c
@@ -43,10 +43,10 @@ static rt_err_t _wait_ready(struct rt_spi_device *device);
 static rt_err_t  rt_msd_init(rt_device_t dev);
 static rt_err_t  rt_msd_open(rt_device_t dev, rt_uint16_t oflag);
 static rt_err_t  rt_msd_close(rt_device_t dev);
-static rt_size_t rt_msd_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
-static rt_size_t rt_msd_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-static rt_size_t rt_msd_sdhc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-static rt_size_t rt_msd_sdhc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+static rt_ssize_t rt_msd_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+static rt_ssize_t rt_msd_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+static rt_ssize_t rt_msd_sdhc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+static rt_ssize_t rt_msd_sdhc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 static rt_err_t rt_msd_control(rt_device_t dev, int cmd, void *args);
 
 static rt_err_t MSD_take_owner(struct rt_spi_device *spi_device)
@@ -1209,7 +1209,7 @@ static rt_err_t rt_msd_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_msd_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_msd_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     struct msd_device *msd = (struct msd_device *)dev;
     uint8_t response[MSD_RESPONSE_MAX_LEN];
@@ -1285,7 +1285,7 @@ _exit:
     return size;
 }
 
-static rt_size_t rt_msd_sdhc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rt_msd_sdhc_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     struct msd_device *msd = (struct msd_device *)dev;
     uint8_t response[MSD_RESPONSE_MAX_LEN];
@@ -1361,7 +1361,7 @@ _exit:
     return size;
 }
 
-static rt_size_t rt_msd_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_msd_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     struct msd_device *msd = (struct msd_device *)dev;
     uint8_t response[MSD_RESPONSE_MAX_LEN];
@@ -1481,7 +1481,7 @@ _exit:
     return size;
 }
 
-static rt_size_t rt_msd_sdhc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rt_msd_sdhc_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     struct msd_device *msd = (struct msd_device *)dev;
     uint8_t response[MSD_RESPONSE_MAX_LEN];
diff --git a/components/drivers/spi/spi_wifi_rw009.c b/components/drivers/spi/spi_wifi_rw009.c
index 39388f10c4..6cbe8dbaa9 100644
--- a/components/drivers/spi/spi_wifi_rw009.c
+++ b/components/drivers/spi/spi_wifi_rw009.c
@@ -504,13 +504,13 @@ static rt_err_t rw009_wifi_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rw009_wifi_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t rw009_wifi_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rw009_wifi_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t rw009_wifi_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/components/drivers/touch/touch.c b/components/drivers/touch/touch.c
index 6f5b73a7cb..e15ebf5b05 100644
--- a/components/drivers/touch/touch.c
+++ b/components/drivers/touch/touch.c
@@ -122,7 +122,7 @@ static rt_err_t rt_touch_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_touch_read(rt_device_t dev, rt_off_t pos, void *buf, rt_size_t len)
+static rt_ssize_t rt_touch_read(rt_device_t dev, rt_off_t pos, void *buf, rt_size_t len)
 {
     rt_touch_t touch;
     rt_size_t result = 0;
diff --git a/components/drivers/tty/console.c b/components/drivers/tty/console.c
index dfab484f2e..01349635b4 100644
--- a/components/drivers/tty/console.c
+++ b/components/drivers/tty/console.c
@@ -197,7 +197,7 @@ static rt_err_t rt_console_close(struct rt_device *dev)
     return result;
 }
 
-static rt_size_t rt_console_read(struct rt_device *dev,
+static rt_ssize_t rt_console_read(struct rt_device *dev,
         rt_off_t          pos,
         void             *buffer,
         rt_size_t         size)
@@ -206,7 +206,7 @@ static rt_size_t rt_console_read(struct rt_device *dev,
     return len;
 }
 
-static rt_size_t rt_console_write(struct rt_device *dev,
+static rt_ssize_t rt_console_write(struct rt_device *dev,
         rt_off_t          pos,
         const void       *buffer,
         rt_size_t         size)
diff --git a/components/drivers/tty/pty.c b/components/drivers/tty/pty.c
index 34b366f399..46a241a715 100644
--- a/components/drivers/tty/pty.c
+++ b/components/drivers/tty/pty.c
@@ -123,7 +123,7 @@ static rt_err_t pty_device_close(struct rt_device *dev)
     return result;
 }
 
-static rt_size_t pty_device_read(struct rt_device *dev,
+static rt_ssize_t pty_device_read(struct rt_device *dev,
         rt_off_t          pos,
         void             *buffer,
         rt_size_t         size)
@@ -133,7 +133,7 @@ static rt_size_t pty_device_read(struct rt_device *dev,
     return len;
 }
 
-static rt_size_t pty_device_write(struct rt_device *dev,
+static rt_ssize_t pty_device_write(struct rt_device *dev,
         rt_off_t          pos,
         const void       *buffer,
         rt_size_t         size)
diff --git a/components/drivers/usb/usbdevice/class/cdc_vcom.c b/components/drivers/usb/usbdevice/class/cdc_vcom.c
index 89d03caf88..29d3e25174 100644
--- a/components/drivers/usb/usbdevice/class/cdc_vcom.c
+++ b/components/drivers/usb/usbdevice/class/cdc_vcom.c
@@ -721,7 +721,7 @@ static int _vcom_getc(struct rt_serial_device *serial)
     return result;
 }
 
-static rt_size_t _vcom_rb_block_put(struct vcom *data, const rt_uint8_t *buf, rt_size_t size)
+static rt_ssize_t _vcom_rb_block_put(struct vcom *data, const rt_uint8_t *buf, rt_size_t size)
 {
     rt_base_t level;
     rt_size_t   put_len = 0;
@@ -751,7 +751,7 @@ static rt_size_t _vcom_rb_block_put(struct vcom *data, const rt_uint8_t *buf, rt
     return size;
 }
 
-static rt_size_t _vcom_tx(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+static rt_ssize_t _vcom_tx(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
 {
     struct ufunction *func;
     struct vcom *data;
diff --git a/components/drivers/usb/usbdevice/class/ecm.c b/components/drivers/usb/usbdevice/class/ecm.c
index 4f41c00531..f821a9969e 100644
--- a/components/drivers/usb/usbdevice/class/ecm.c
+++ b/components/drivers/usb/usbdevice/class/ecm.c
@@ -324,13 +324,13 @@ static rt_err_t rt_ecm_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_ecm_eth_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_ecm_eth_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_ecm_eth_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_ecm_eth_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/components/drivers/usb/usbdevice/class/hid.c b/components/drivers/usb/usbdevice/class/hid.c
index a95e1d82e5..d2bb05ed24 100644
--- a/components/drivers/usb/usbdevice/class/hid.c
+++ b/components/drivers/usb/usbdevice/class/hid.c
@@ -594,7 +594,7 @@ static rt_err_t _hid_descriptor_config(uhid_comm_desc_t hid, rt_uint8_t cintf_nr
 
     return RT_EOK;
 }
-static rt_size_t _hid_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t _hid_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     struct hid_s *hiddev = (struct hid_s *)dev;
     struct hid_report report;
diff --git a/components/drivers/usb/usbdevice/class/mstorage.c b/components/drivers/usb/usbdevice/class/mstorage.c
index b8f21a29df..96a1299890 100644
--- a/components/drivers/usb/usbdevice/class/mstorage.c
+++ b/components/drivers/usb/usbdevice/class/mstorage.c
@@ -44,7 +44,7 @@ typedef enum
     DIR_NONE,
 }CB_DIR;
 
-typedef rt_size_t (*cbw_handler)(ufunction_t func, ustorage_cbw_t cbw);
+typedef rt_ssize_t (*cbw_handler)(ufunction_t func, ustorage_cbw_t cbw);
 
 struct scsi_cmd
 {
@@ -168,17 +168,17 @@ const static char* _ustring[] =
     "Interface",
 };
 
-static rt_size_t _test_unit_ready(ufunction_t func, ustorage_cbw_t cbw);
-static rt_size_t _request_sense(ufunction_t func, ustorage_cbw_t cbw);
-static rt_size_t _inquiry_cmd(ufunction_t func, ustorage_cbw_t cbw);
-static rt_size_t _allow_removal(ufunction_t func, ustorage_cbw_t cbw);
-static rt_size_t _start_stop(ufunction_t func, ustorage_cbw_t cbw);
-static rt_size_t _mode_sense_6(ufunction_t func, ustorage_cbw_t cbw);
-static rt_size_t _read_capacities(ufunction_t func, ustorage_cbw_t cbw);
-static rt_size_t _read_capacity(ufunction_t func, ustorage_cbw_t cbw);
-static rt_size_t _read_10(ufunction_t func, ustorage_cbw_t cbw);
-static rt_size_t _write_10(ufunction_t func, ustorage_cbw_t cbw);
-static rt_size_t _verify_10(ufunction_t func, ustorage_cbw_t cbw);
+static rt_ssize_t _test_unit_ready(ufunction_t func, ustorage_cbw_t cbw);
+static rt_ssize_t _request_sense(ufunction_t func, ustorage_cbw_t cbw);
+static rt_ssize_t _inquiry_cmd(ufunction_t func, ustorage_cbw_t cbw);
+static rt_ssize_t _allow_removal(ufunction_t func, ustorage_cbw_t cbw);
+static rt_ssize_t _start_stop(ufunction_t func, ustorage_cbw_t cbw);
+static rt_ssize_t _mode_sense_6(ufunction_t func, ustorage_cbw_t cbw);
+static rt_ssize_t _read_capacities(ufunction_t func, ustorage_cbw_t cbw);
+static rt_ssize_t _read_capacity(ufunction_t func, ustorage_cbw_t cbw);
+static rt_ssize_t _read_10(ufunction_t func, ustorage_cbw_t cbw);
+static rt_ssize_t _write_10(ufunction_t func, ustorage_cbw_t cbw);
+static rt_ssize_t _verify_10(ufunction_t func, ustorage_cbw_t cbw);
 
 rt_align(4)
 static struct scsi_cmd cmd_data[] =
@@ -212,7 +212,7 @@ static void _send_status(ufunction_t func)
     data->status = STAT_CSW;
 }
 
-static rt_size_t _test_unit_ready(ufunction_t func, ustorage_cbw_t cbw)
+static rt_ssize_t _test_unit_ready(ufunction_t func, ustorage_cbw_t cbw)
 {
     struct mstorage *data;
 
@@ -227,7 +227,7 @@ static rt_size_t _test_unit_ready(ufunction_t func, ustorage_cbw_t cbw)
     return 0;
 }
 
-static rt_size_t _allow_removal(ufunction_t func, ustorage_cbw_t cbw)
+static rt_ssize_t _allow_removal(ufunction_t func, ustorage_cbw_t cbw)
 {
     struct mstorage *data;
 
@@ -251,7 +251,7 @@ static rt_size_t _allow_removal(ufunction_t func, ustorage_cbw_t cbw)
  * @return RT_EOK on successful.
  */
 
-static rt_size_t _inquiry_cmd(ufunction_t func, ustorage_cbw_t cbw)
+static rt_ssize_t _inquiry_cmd(ufunction_t func, ustorage_cbw_t cbw)
 {
     struct mstorage *data;
     rt_uint8_t *buf;
@@ -290,7 +290,7 @@ static rt_size_t _inquiry_cmd(ufunction_t func, ustorage_cbw_t cbw)
  *
  * @return RT_EOK on successful.
  */
-static rt_size_t _request_sense(ufunction_t func, ustorage_cbw_t cbw)
+static rt_ssize_t _request_sense(ufunction_t func, ustorage_cbw_t cbw)
 {
     struct mstorage *data;
     struct request_sense_data *buf;
@@ -333,7 +333,7 @@ static rt_size_t _request_sense(ufunction_t func, ustorage_cbw_t cbw)
  *
  * @return RT_EOK on successful.
  */
-static rt_size_t _mode_sense_6(ufunction_t func, ustorage_cbw_t cbw)
+static rt_ssize_t _mode_sense_6(ufunction_t func, ustorage_cbw_t cbw)
 {
     struct mstorage *data;
     rt_uint8_t *buf;
@@ -369,7 +369,7 @@ static rt_size_t _mode_sense_6(ufunction_t func, ustorage_cbw_t cbw)
  *
  * @return RT_EOK on successful.
  */
-static rt_size_t _read_capacities(ufunction_t func, ustorage_cbw_t cbw)
+static rt_ssize_t _read_capacities(ufunction_t func, ustorage_cbw_t cbw)
 {
     struct mstorage *data;
     rt_uint8_t *buf;
@@ -414,7 +414,7 @@ static rt_size_t _read_capacities(ufunction_t func, ustorage_cbw_t cbw)
  *
  * @return RT_EOK on successful.
  */
-static rt_size_t _read_capacity(ufunction_t func, ustorage_cbw_t cbw)
+static rt_ssize_t _read_capacity(ufunction_t func, ustorage_cbw_t cbw)
 {
     struct mstorage *data;
 
@@ -459,7 +459,7 @@ static rt_size_t _read_capacity(ufunction_t func, ustorage_cbw_t cbw)
  *
  * @return RT_EOK on successful.
  */
-static rt_size_t _read_10(ufunction_t func, ustorage_cbw_t cbw)
+static rt_ssize_t _read_10(ufunction_t func, ustorage_cbw_t cbw)
 {
     struct mstorage *data;
     rt_size_t size;
@@ -499,7 +499,7 @@ static rt_size_t _read_10(ufunction_t func, ustorage_cbw_t cbw)
  *
  * @return RT_EOK on successful.
  */
-static rt_size_t _write_10(ufunction_t func, ustorage_cbw_t cbw)
+static rt_ssize_t _write_10(ufunction_t func, ustorage_cbw_t cbw)
 {
     struct mstorage *data;
 
@@ -536,7 +536,7 @@ static rt_size_t _write_10(ufunction_t func, ustorage_cbw_t cbw)
  *
  * @return RT_EOK on successful.
  */
-static rt_size_t _verify_10(ufunction_t func, ustorage_cbw_t cbw)
+static rt_ssize_t _verify_10(ufunction_t func, ustorage_cbw_t cbw)
 {
     struct mstorage *data;
 
@@ -551,7 +551,7 @@ static rt_size_t _verify_10(ufunction_t func, ustorage_cbw_t cbw)
     return 0;
 }
 
-static rt_size_t _start_stop(ufunction_t func,
+static rt_ssize_t _start_stop(ufunction_t func,
     ustorage_cbw_t cbw)
 {
     struct mstorage *data;
@@ -795,7 +795,7 @@ static rt_bool_t _cbw_verify(ufunction_t func, struct scsi_cmd* cmd,
     return RT_TRUE;
 }
 
-static rt_size_t _cbw_handler(ufunction_t func, struct scsi_cmd* cmd,
+static rt_ssize_t _cbw_handler(ufunction_t func, struct scsi_cmd* cmd,
     ustorage_cbw_t cbw)
 {
     struct mstorage *data;
diff --git a/components/drivers/usb/usbdevice/class/rndis.c b/components/drivers/usb/usbdevice/class/rndis.c
index 425ff62ee1..449957db2e 100644
--- a/components/drivers/usb/usbdevice/class/rndis.c
+++ b/components/drivers/usb/usbdevice/class/rndis.c
@@ -1083,13 +1083,13 @@ static rt_err_t rt_rndis_eth_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_rndis_eth_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_rndis_eth_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
 }
 
-static rt_size_t rt_rndis_eth_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_rndis_eth_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_set_errno(-RT_ENOSYS);
     return 0;
diff --git a/components/drivers/usb/usbdevice/class/winusb.c b/components/drivers/usb/usbdevice/class/winusb.c
index 4e534399be..cf72ce8d84 100644
--- a/components/drivers/usb/usbdevice/class/winusb.c
+++ b/components/drivers/usb/usbdevice/class/winusb.c
@@ -227,7 +227,7 @@ static rt_err_t _winusb_descriptor_config(winusb_desc_t winusb, rt_uint8_t cintf
     return RT_EOK;
 }
 
-static rt_size_t win_usb_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t win_usb_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     if(((ufunction_t)dev->user_data)->device->state != USB_STATE_CONFIGURED)
     {
@@ -241,7 +241,7 @@ static rt_size_t win_usb_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_si
     rt_usbd_io_request(((ufunction_t)dev->user_data)->device,winusb_device->ep_out,&winusb_device->ep_out->request);
     return size;
 }
-static rt_size_t win_usb_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t win_usb_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     if(((ufunction_t)dev->user_data)->device->state != USB_STATE_CONFIGURED)
     {
diff --git a/components/drivers/usb/usbdevice/core/usbdevice_core.c b/components/drivers/usb/usbdevice/core/usbdevice_core.c
index 58d7170012..03f231dcef 100644
--- a/components/drivers/usb/usbdevice/core/usbdevice_core.c
+++ b/components/drivers/usb/usbdevice/core/usbdevice_core.c
@@ -19,8 +19,8 @@
 
 static rt_list_t device_list;
 
-static rt_size_t rt_usbd_ep_write(udevice_t device, uep_t ep, void *buffer, rt_size_t size);
-static rt_size_t rt_usbd_ep_read_prepare(udevice_t device, uep_t ep, void *buffer, rt_size_t size);
+static rt_ssize_t rt_usbd_ep_write(udevice_t device, uep_t ep, void *buffer, rt_size_t size);
+static rt_ssize_t rt_usbd_ep_read_prepare(udevice_t device, uep_t ep, void *buffer, rt_size_t size);
 static rt_err_t rt_usbd_ep_assign(udevice_t device, uep_t ep);
 rt_err_t rt_usbd_ep_unassign(udevice_t device, uep_t ep);
 
@@ -962,7 +962,7 @@ static rt_err_t _stop_notify(udevice_t device)
     return RT_EOK;
 }
 
-static rt_size_t rt_usbd_ep_write(udevice_t device, uep_t ep, void *buffer, rt_size_t size)
+static rt_ssize_t rt_usbd_ep_write(udevice_t device, uep_t ep, void *buffer, rt_size_t size)
 {
     rt_uint16_t maxpacket;
 
@@ -988,7 +988,7 @@ static rt_size_t rt_usbd_ep_write(udevice_t device, uep_t ep, void *buffer, rt_s
     return size;
 }
 
-static rt_size_t rt_usbd_ep_read_prepare(udevice_t device, uep_t ep, void *buffer, rt_size_t size)
+static rt_ssize_t rt_usbd_ep_read_prepare(udevice_t device, uep_t ep, void *buffer, rt_size_t size)
 {
     RT_ASSERT(device != RT_NULL);
     RT_ASSERT(device->dcd != RT_NULL);
diff --git a/components/drivers/usb/usbhost/class/adk.c b/components/drivers/usb/usbhost/class/adk.c
index 492a2f9bb7..3475214789 100644
--- a/components/drivers/usb/usbhost/class/adk.c
+++ b/components/drivers/usb/usbhost/class/adk.c
@@ -149,7 +149,7 @@ static rt_err_t rt_usbh_adk_start(struct uintf* intf)
  *
  * @return the error code, RT_EOK on successfully.
 */
-static rt_size_t rt_usbh_adk_read(rt_device_t device, rt_off_t pos, void* buffer,
+static rt_ssize_t rt_usbh_adk_read(rt_device_t device, rt_off_t pos, void* buffer,
     rt_size_t size)
 {
     uadk_t adk;
@@ -177,7 +177,7 @@ static rt_size_t rt_usbh_adk_read(rt_device_t device, rt_off_t pos, void* buffer
  *
  * @return the error code, RT_EOK on successfully.
 */
-static rt_size_t rt_usbh_adk_write (rt_device_t device, rt_off_t pos, const void* buffer,
+static rt_ssize_t rt_usbh_adk_write (rt_device_t device, rt_off_t pos, const void* buffer,
     rt_size_t size)
 {
     uadk_t adk;
diff --git a/components/drivers/usb/usbhost/class/udisk.c b/components/drivers/usb/usbhost/class/udisk.c
index 8be311e657..ee0129b487 100644
--- a/components/drivers/usb/usbhost/class/udisk.c
+++ b/components/drivers/usb/usbhost/class/udisk.c
@@ -64,7 +64,7 @@ static rt_err_t rt_udisk_init(rt_device_t dev)
  *
  * @return the actually read size on successful, otherwise negative returned.
  */
-static rt_size_t rt_udisk_read(rt_device_t dev, rt_off_t pos, void* buffer,
+static rt_ssize_t rt_udisk_read(rt_device_t dev, rt_off_t pos, void* buffer,
     rt_size_t size)
 {
     rt_err_t ret;
@@ -102,7 +102,7 @@ static rt_size_t rt_udisk_read(rt_device_t dev, rt_off_t pos, void* buffer,
  *
  * @return the actually written size on successful, otherwise negative returned.
  */
-static rt_size_t rt_udisk_write (rt_device_t dev, rt_off_t pos, const void* buffer,
+static rt_ssize_t rt_udisk_write (rt_device_t dev, rt_off_t pos, const void* buffer,
     rt_size_t size)
 {
     rt_err_t ret;
diff --git a/components/drivers/virtio/virtio_blk.c b/components/drivers/virtio/virtio_blk.c
index a568a7008a..41e03e39d4 100644
--- a/components/drivers/virtio/virtio_blk.c
+++ b/components/drivers/virtio/virtio_blk.c
@@ -82,14 +82,14 @@ static void virtio_blk_rw(struct virtio_blk_device *virtio_blk_dev, rt_off_t pos
 #endif
 }
 
-static rt_size_t virtio_blk_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t count)
+static rt_ssize_t virtio_blk_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t count)
 {
     virtio_blk_rw((struct virtio_blk_device *)dev, pos, buffer, count, VIRTIO_BLK_T_IN);
 
     return count;
 }
 
-static rt_size_t virtio_blk_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t count)
+static rt_ssize_t virtio_blk_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t count)
 {
     virtio_blk_rw((struct virtio_blk_device *)dev, pos, (void *)buffer, count, VIRTIO_BLK_T_OUT);
 
diff --git a/components/drivers/virtio/virtio_console.c b/components/drivers/virtio/virtio_console.c
index 7f1a9b8af5..ac6c821853 100644
--- a/components/drivers/virtio/virtio_console.c
+++ b/components/drivers/virtio/virtio_console.c
@@ -78,8 +78,8 @@ static void virtio_console_send_ctrl(struct virtio_console_device *virtio_consol
 static rt_err_t virtio_console_port_init(rt_device_t dev);
 static rt_err_t virtio_console_port_open(rt_device_t dev, rt_uint16_t oflag);
 static rt_err_t virtio_console_port_close(rt_device_t dev);
-static rt_size_t virtio_console_port_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-static rt_size_t virtio_console_port_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+static rt_ssize_t virtio_console_port_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+static rt_ssize_t virtio_console_port_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
 static rt_err_t virtio_console_port_control(rt_device_t dev, int cmd, void *args);
 
 #ifdef RT_USING_DEVICE_OPS
@@ -295,7 +295,7 @@ static rt_err_t virtio_console_port_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t virtio_console_port_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t virtio_console_port_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_off_t i = 0;
     rt_uint16_t id;
@@ -346,7 +346,7 @@ static rt_size_t virtio_console_port_read(rt_device_t dev, rt_off_t pos, void *b
     return size;
 }
 
-static rt_size_t virtio_console_port_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t virtio_console_port_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     char ch = 0;
     rt_off_t i = 0;
diff --git a/components/drivers/virtio/virtio_gpu.c b/components/drivers/virtio/virtio_gpu.c
index 67ce28a876..a9836d9b7a 100644
--- a/components/drivers/virtio/virtio_gpu.c
+++ b/components/drivers/virtio/virtio_gpu.c
@@ -448,7 +448,7 @@ static rt_err_t virtio_gpu_init(rt_device_t dev)
     return status;
 }
 
-static rt_size_t virtio_gpu_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t virtio_gpu_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     struct virtio_gpu_device *virtio_gpu_dev = (struct virtio_gpu_device *)dev;
 
@@ -466,7 +466,7 @@ static rt_size_t virtio_gpu_read(rt_device_t dev, rt_off_t pos, void *buffer, rt
     return size;
 }
 
-static rt_size_t virtio_gpu_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t virtio_gpu_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     struct virtio_gpu_device *virtio_gpu_dev = (struct virtio_gpu_device *)dev;
 
diff --git a/components/drivers/virtio/virtio_input.c b/components/drivers/virtio/virtio_input.c
index 8de3d9c83f..41ecd6bb83 100644
--- a/components/drivers/virtio/virtio_input.c
+++ b/components/drivers/virtio/virtio_input.c
@@ -24,7 +24,7 @@ static void _set_bit(rt_uint32_t nr, volatile rt_ubase_t *addr)
     *p  |= mask;
 }
 
-static rt_size_t virtio_input_cfg_select(struct virtio_input_device *virtio_input_dev,
+static rt_ssize_t virtio_input_cfg_select(struct virtio_input_device *virtio_input_dev,
         rt_uint8_t select, rt_uint8_t subsel)
 {
     struct virtio_input_config *config = virtio_input_dev->config;
@@ -139,7 +139,7 @@ static rt_err_t virtio_input_init(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t virtio_input_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t virtio_input_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     struct virtio_input_device *virtio_input_dev = (struct virtio_input_device *)dev;
 
@@ -157,7 +157,7 @@ static rt_size_t virtio_input_read(rt_device_t dev, rt_off_t pos, void *buffer,
     return size;
 }
 
-static rt_size_t virtio_input_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t virtio_input_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     struct virtio_input_device *virtio_input_dev = (struct virtio_input_device *)dev;
 
diff --git a/components/fal/src/fal_rtt.c b/components/fal/src/fal_rtt.c
index 3473bc233a..a40832f31c 100644
--- a/components/fal/src/fal_rtt.c
+++ b/components/fal/src/fal_rtt.c
@@ -75,7 +75,7 @@ static rt_err_t blk_dev_control(rt_device_t dev, rt_uint8_t cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t blk_dev_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t blk_dev_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     int ret = 0;
     struct fal_blk_device *part = (struct fal_blk_device*) dev;
@@ -96,7 +96,7 @@ static rt_size_t blk_dev_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_si
     return ret;
 }
 
-static rt_size_t blk_dev_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t blk_dev_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     int ret = 0;
     struct fal_blk_device *part;
@@ -212,7 +212,7 @@ struct fal_mtd_nor_device
     const struct fal_partition     *fal_part;
 };
 
-static rt_size_t mtd_nor_dev_read(struct rt_mtd_nor_device* device, rt_off_t offset, rt_uint8_t* data, rt_uint32_t length)
+static rt_ssize_t mtd_nor_dev_read(struct rt_mtd_nor_device* device, rt_off_t offset, rt_uint8_t* data, rt_uint32_t length)
 {
     int ret = 0;
     struct fal_mtd_nor_device *part = (struct fal_mtd_nor_device*) device;
@@ -233,7 +233,7 @@ static rt_size_t mtd_nor_dev_read(struct rt_mtd_nor_device* device, rt_off_t off
     return ret;
 }
 
-static rt_size_t mtd_nor_dev_write(struct rt_mtd_nor_device* device, rt_off_t offset, const rt_uint8_t* data, rt_uint32_t length)
+static rt_ssize_t mtd_nor_dev_write(struct rt_mtd_nor_device* device, rt_off_t offset, const rt_uint8_t* data, rt_uint32_t length)
 {
     int ret = 0;
     struct fal_mtd_nor_device *part;
@@ -343,7 +343,7 @@ struct fal_char_device
 };
 
 /* RT-Thread device interface */
-static rt_size_t char_dev_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t char_dev_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     int ret = 0;
     struct fal_char_device *part = (struct fal_char_device *) dev;
@@ -361,7 +361,7 @@ static rt_size_t char_dev_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_s
     return ret;
 }
 
-static rt_size_t char_dev_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t char_dev_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     int ret = 0;
     struct fal_char_device *part;
diff --git a/components/lwp/lwp_syscall.c b/components/lwp/lwp_syscall.c
index 85e641e395..5a2d0d4263 100644
--- a/components/lwp/lwp_syscall.c
+++ b/components/lwp/lwp_syscall.c
@@ -2675,12 +2675,12 @@ rt_err_t sys_device_close(rt_device_t dev)
     return rt_device_close(dev);
 }
 
-rt_size_t sys_device_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+rt_ssize_t sys_device_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     return rt_device_read(dev, pos, buffer, size);
 }
 
-rt_size_t sys_device_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+rt_ssize_t sys_device_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     return rt_device_write(dev, pos, buffer, size);
 }
diff --git a/components/utilities/rt-link/src/rtlink.c b/components/utilities/rt-link/src/rtlink.c
index e4aa08824d..48d91fc94b 100644
--- a/components/utilities/rt-link/src/rtlink.c
+++ b/components/utilities/rt-link/src/rtlink.c
@@ -208,7 +208,7 @@ static void rt_link_service_send_finish(rt_link_err_e err)
     }
 }
 
-static rt_size_t frame_send(struct rt_link_frame *frame)
+static rt_ssize_t frame_send(struct rt_link_frame *frame)
 {
     rt_size_t length = 0;
     rt_uint8_t *data = RT_NULL;
diff --git a/components/utilities/rt-link/src/rtlink_dev.c b/components/utilities/rt-link/src/rtlink_dev.c
index f15294fc4d..24c45585ea 100644
--- a/components/utilities/rt-link/src/rtlink_dev.c
+++ b/components/utilities/rt-link/src/rtlink_dev.c
@@ -265,7 +265,7 @@ rt_err_t  rt_link_dev_close(rt_device_t dev)
     return rt_link_service_detach(&rtlink->service);
 }
 
-rt_size_t rt_link_dev_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+rt_ssize_t rt_link_dev_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
     RT_ASSERT(buffer != RT_NULL);
@@ -305,7 +305,7 @@ rt_size_t rt_link_dev_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_
     return read_len;
 }
 
-rt_size_t rt_link_dev_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+rt_ssize_t rt_link_dev_write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     RT_ASSERT(dev != RT_NULL);
     RT_ASSERT(buffer != RT_NULL);
diff --git a/components/utilities/rt-link/src/rtlink_hw.c b/components/utilities/rt-link/src/rtlink_hw.c
index 4a56ea4893..847100912e 100644
--- a/components/utilities/rt-link/src/rtlink_hw.c
+++ b/components/utilities/rt-link/src/rtlink_hw.c
@@ -45,7 +45,7 @@ struct rt_link_receive_buffer *rt_link_hw_buffer_init(void *parameter)
     return rx_buffer;
 }
 
-static rt_size_t rt_link_hw_buffer_write(void *data, rt_size_t count)
+static rt_ssize_t rt_link_hw_buffer_write(void *data, rt_size_t count)
 {
     rt_size_t surplus = 0;
     if (rx_buffer == RT_NULL)
diff --git a/components/utilities/ymodem/ymodem.c b/components/utilities/ymodem/ymodem.c
index efbb70defd..f554d81f98 100644
--- a/components/utilities/ymodem/ymodem.c
+++ b/components/utilities/ymodem/ymodem.c
@@ -121,7 +121,7 @@ static enum rym_code _rym_read_code(
 }
 
 /* the caller should at least alloc _RYM_STX_PKG_SZ buffer */
-static rt_size_t _rym_read_data(
+static rt_ssize_t _rym_read_data(
     struct rym_ctx *ctx,
     rt_size_t len)
 {
@@ -180,13 +180,13 @@ static rt_err_t _rym_send_packet(
     return RT_EOK;
 }
 
-static rt_size_t _rym_putchar(struct rym_ctx *ctx, rt_uint8_t code)
+static rt_ssize_t _rym_putchar(struct rym_ctx *ctx, rt_uint8_t code)
 {
     rt_device_write(ctx->dev, 0, &code, sizeof(code));
     return 1;
 }
 
-static rt_size_t _rym_getchar(struct rym_ctx *ctx)
+static rt_ssize_t _rym_getchar(struct rym_ctx *ctx)
 {
     rt_uint8_t getc_ack;
 
diff --git a/components/vbus/vbus_chnx.c b/components/vbus/vbus_chnx.c
index 1014369cc2..d9bb3e4d46 100644
--- a/components/vbus/vbus_chnx.c
+++ b/components/vbus/vbus_chnx.c
@@ -62,7 +62,7 @@ static rt_err_t _close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t _read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
+static rt_ssize_t _read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
 {
     rt_size_t outsz = 0;
     struct rt_vbus_dev *vdev = dev->user_data;
@@ -126,7 +126,7 @@ static rt_size_t _read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t si
     }
 }
 
-static rt_size_t _write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
+static rt_ssize_t _write(rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
 {
     rt_err_t err;
     struct rt_vbus_dev *vdev = dev->user_data;
diff --git a/documentation/device/device.md b/documentation/device/device.md
index 33887d3fe6..2f24f61304 100644
--- a/documentation/device/device.md
+++ b/documentation/device/device.md
@@ -120,8 +120,8 @@ struct rt_device_ops
     rt_err_t  (*init)   (rt_device_t dev);
     rt_err_t  (*open)   (rt_device_t dev, rt_uint16_t oflag);
     rt_err_t  (*close)  (rt_device_t dev);
-    rt_size_t (*read)   (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-    rt_size_t (*write)  (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+    rt_ssize_t (*read)  (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+    rt_ssize_t (*write) (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
     rt_err_t  (*control)(rt_device_t dev, int cmd, void *args);
 };
 
diff --git a/include/rtdef.h b/include/rtdef.h
index 31341759bf..4a65c27842 100644
--- a/include/rtdef.h
+++ b/include/rtdef.h
@@ -1217,8 +1217,8 @@ struct rt_device_ops
     rt_err_t  (*init)   (rt_device_t dev);
     rt_err_t  (*open)   (rt_device_t dev, rt_uint16_t oflag);
     rt_err_t  (*close)  (rt_device_t dev);
-    rt_size_t (*read)   (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-    rt_size_t (*write)  (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+    rt_ssize_t (*read)  (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+    rt_ssize_t (*write) (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
     rt_err_t  (*control)(rt_device_t dev, int cmd, void *args);
 };
 #endif /* RT_USING_DEVICE_OPS */
@@ -1261,8 +1261,8 @@ struct rt_device
     rt_err_t  (*init)   (rt_device_t dev);
     rt_err_t  (*open)   (rt_device_t dev, rt_uint16_t oflag);
     rt_err_t  (*close)  (rt_device_t dev);
-    rt_size_t (*read)   (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-    rt_size_t (*write)  (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+    rt_ssize_t (*read)  (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+    rt_ssize_t (*write) (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
     rt_err_t  (*control)(rt_device_t dev, int cmd, void *args);
 #endif /* RT_USING_DEVICE_OPS */
 
@@ -1290,8 +1290,8 @@ struct rt_driver
     rt_err_t  (*init)   (rt_device_t dev);
     rt_err_t  (*open)   (rt_device_t dev, rt_uint16_t oflag);
     rt_err_t  (*close)  (rt_device_t dev);
-    rt_size_t (*read)   (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
-    rt_size_t (*write)  (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
+    rt_ssize_t (*read)  (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
+    rt_ssize_t (*write) (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
     rt_err_t  (*control)(rt_device_t dev, int cmd, void *args);
 #endif
     const struct filesystem_ops *fops;
diff --git a/include/rtthread.h b/include/rtthread.h
index 7538a3c032..5cfa3c26b1 100644
--- a/include/rtthread.h
+++ b/include/rtthread.h
@@ -560,11 +560,11 @@ rt_device_set_tx_complete(rt_device_t dev,
 rt_err_t  rt_device_init (rt_device_t dev);
 rt_err_t  rt_device_open (rt_device_t dev, rt_uint16_t oflag);
 rt_err_t  rt_device_close(rt_device_t dev);
-rt_size_t rt_device_read (rt_device_t dev,
+rt_ssize_t rt_device_read(rt_device_t dev,
                           rt_off_t    pos,
                           void       *buffer,
                           rt_size_t   size);
-rt_size_t rt_device_write(rt_device_t dev,
+rt_ssize_t rt_device_write(rt_device_t dev,
                           rt_off_t    pos,
                           const void *buffer,
                           rt_size_t   size);
diff --git a/libcpu/arm/AT91SAM7S/serial.c b/libcpu/arm/AT91SAM7S/serial.c
index 583443f4cb..92ed2bac3d 100644
--- a/libcpu/arm/AT91SAM7S/serial.c
+++ b/libcpu/arm/AT91SAM7S/serial.c
@@ -215,7 +215,7 @@ static rt_err_t rt_serial_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     struct rt_at91serial *serial = (struct rt_at91serial*)dev;
@@ -283,7 +283,7 @@ static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt
     return 0;
 }
 
-static rt_size_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     struct rt_at91serial *serial = (struct rt_at91serial*)dev;
diff --git a/libcpu/arm/s3c24x0/rtc.c b/libcpu/arm/s3c24x0/rtc.c
index b7bbba9a55..ba2c45d443 100644
--- a/libcpu/arm/s3c24x0/rtc.c
+++ b/libcpu/arm/s3c24x0/rtc.c
@@ -119,7 +119,7 @@ static rt_err_t rtc_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rtc_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rtc_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     return RT_EOK;
 }
diff --git a/libcpu/arm/sep4020/serial.c b/libcpu/arm/sep4020/serial.c
index 9bf1546c08..964403b1e3 100644
--- a/libcpu/arm/sep4020/serial.c
+++ b/libcpu/arm/sep4020/serial.c
@@ -86,7 +86,7 @@ static rt_err_t rt_serial_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     rt_err_t err_code;
@@ -144,7 +144,7 @@ static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt
     return (rt_uint32_t)ptr - (rt_uint32_t)buffer;
 }
 
-static rt_size_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     rt_err_t err_code;
diff --git a/libcpu/avr32/uc3/serial.c b/libcpu/avr32/uc3/serial.c
index 5228d3e734..aa63ae846f 100644
--- a/libcpu/avr32/uc3/serial.c
+++ b/libcpu/avr32/uc3/serial.c
@@ -59,7 +59,7 @@ static rt_err_t rt_serial_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     rt_err_t err_code;
@@ -122,7 +122,7 @@ static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt
     return (rt_uint32_t)ptr - (rt_uint32_t)buffer;
 }
 
-static rt_size_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     rt_err_t err_code;
diff --git a/libcpu/blackfin/bf53x/serial.c b/libcpu/blackfin/bf53x/serial.c
index 4a6484a647..f30ce4f203 100644
--- a/libcpu/blackfin/bf53x/serial.c
+++ b/libcpu/blackfin/bf53x/serial.c
@@ -93,7 +93,7 @@ static rt_err_t rt_serial_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     rt_err_t err_code;
@@ -151,7 +151,7 @@ static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt
     return (rt_uint32_t)ptr - (rt_uint32_t)buffer;
 }
 
-static rt_size_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     rt_err_t err_code;
diff --git a/libcpu/ppc/ppc405/serial.c b/libcpu/ppc/ppc405/serial.c
index 1fc9039769..3112a1823b 100644
--- a/libcpu/ppc/ppc405/serial.c
+++ b/libcpu/ppc/ppc405/serial.c
@@ -99,7 +99,7 @@ static rt_err_t rt_serial_control(rt_device_t dev, int cmd, void *args)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     struct rt_ppc405_serial* device;
@@ -156,7 +156,7 @@ static rt_size_t rt_serial_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_
     return (rt_size_t)ptr - (rt_size_t)buffer;
 }
 
-static rt_size_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     char *ptr;
     struct rt_ppc405_serial* device;
diff --git a/libcpu/unicore32/sep6200/serial.c b/libcpu/unicore32/sep6200/serial.c
index f91834b6a7..d732716619 100644
--- a/libcpu/unicore32/sep6200/serial.c
+++ b/libcpu/unicore32/sep6200/serial.c
@@ -84,7 +84,7 @@ static rt_err_t rt_serial_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     rt_err_t err_code;
@@ -142,7 +142,7 @@ static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt
     return (rt_uint32_t)ptr - (rt_uint32_t)buffer;
 }
 
-static rt_size_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     rt_err_t err_code;
diff --git a/libcpu/xilinx/microblaze/serial.c b/libcpu/xilinx/microblaze/serial.c
index 1902f11710..ea0070fb23 100755
--- a/libcpu/xilinx/microblaze/serial.c
+++ b/libcpu/xilinx/microblaze/serial.c
@@ -144,7 +144,7 @@ static rt_err_t rt_serial_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     struct rt_mb_uart_lite *serial = (struct rt_mb_uart_lite*)dev;
@@ -212,7 +212,7 @@ static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt
     return 0;
 }
 
-static rt_size_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     struct rt_mb_uart_lite *serial = (struct rt_mb_uart_lite*)dev;
diff --git a/src/device.c b/src/device.c
index beba062952..9665788c77 100644
--- a/src/device.c
+++ b/src/device.c
@@ -311,7 +311,7 @@ RTM_EXPORT(rt_device_close);
  *
  * @note the unit of size/pos is a block for block device.
  */
-rt_size_t rt_device_read(rt_device_t dev,
+rt_ssize_t rt_device_read(rt_device_t dev,
                          rt_off_t    pos,
                          void       *buffer,
                          rt_size_t   size)
@@ -354,7 +354,7 @@ RTM_EXPORT(rt_device_read);
  *
  * @note the unit of size/pos is a block for block device.
  */
-rt_size_t rt_device_write(rt_device_t dev,
+rt_ssize_t rt_device_write(rt_device_t dev,
                           rt_off_t    pos,
                           const void *buffer,
                           rt_size_t   size)