diff --git a/bsp/qemu-vexpress-a9/cpu/context_gcc.S b/bsp/qemu-vexpress-a9/cpu/context_gcc.S
index 694fb96e72..0aad0200d5 100644
--- a/bsp/qemu-vexpress-a9/cpu/context_gcc.S
+++ b/bsp/qemu-vexpress-a9/cpu/context_gcc.S
@@ -117,7 +117,7 @@ rt_hw_context_switch:
     ldmfd sp!, {r0-r12, lr, pc}^  @ pop new task r0-r12, lr & pc, copy spsr to cpsr
 
 /*
- * void rt_hw_context_switch_interrupt(rt_uint32 from, rt_uint32 to);
+ * void rt_hw_context_switch_interrupt(rt_ubase_t from, rt_ubase_t to);
  */
 .equ Mode_USR,        0x10
 .equ Mode_FIQ,        0x11
diff --git a/bsp/qemu-vexpress-a9/cpu/cpuport.c b/bsp/qemu-vexpress-a9/cpu/cpuport.c
index 22ba8346da..6b129f89ee 100644
--- a/bsp/qemu-vexpress-a9/cpu/cpuport.c
+++ b/bsp/qemu-vexpress-a9/cpu/cpuport.c
@@ -60,14 +60,8 @@ void rt_hw_spin_unlock(rt_hw_spinlock_t *lock)
     lock->tickets.owner++;
     __asm__ volatile ("dsb ishst\nsev":::"memory");
 }
-
 #endif /*RT_USING_SMP*/
 
-void idle_wfi(void)
-{
-    asm volatile ("wfi");
-}
-
 /**
  * @addtogroup ARM CPU
  */
diff --git a/bsp/qemu-vexpress-a9/cpu/interrupt.c b/bsp/qemu-vexpress-a9/cpu/interrupt.c
index d553188e93..d7e9ec08fa 100644
--- a/bsp/qemu-vexpress-a9/cpu/interrupt.c
+++ b/bsp/qemu-vexpress-a9/cpu/interrupt.c
@@ -25,9 +25,9 @@ struct rt_irq_desc isr_table[MAX_HANDLERS];
 
 #ifndef RT_USING_SMP
 /* Those varibles will be accessed in ISR, so we need to share them. */
-rt_uint32_t rt_interrupt_from_thread;
-rt_uint32_t rt_interrupt_to_thread;
-rt_uint32_t rt_thread_switch_interrupt_flag;
+rt_uint32_t rt_interrupt_from_thread        = 0;
+rt_uint32_t rt_interrupt_to_thread          = 0;
+rt_uint32_t rt_thread_switch_interrupt_flag = 0;
 #endif
 
 const unsigned int VECTOR_BASE = 0x00;
@@ -59,13 +59,6 @@ void rt_hw_interrupt_init(void)
 
     arm_gic_dist_init(0, gic_dist_base, 0);
     arm_gic_cpu_init(0, gic_cpu_base);
-
-    /* init interrupt nest, and context in thread sp */
-#ifndef RT_USING_SMP
-    rt_interrupt_from_thread = 0;
-    rt_interrupt_to_thread = 0;
-    rt_thread_switch_interrupt_flag = 0;
-#endif
 }
 
 /**
diff --git a/bsp/qemu-vexpress-a9/drivers/board.c b/bsp/qemu-vexpress-a9/drivers/board.c
index 26445d33f1..6ffac7efd7 100644
--- a/bsp/qemu-vexpress-a9/drivers/board.c
+++ b/bsp/qemu-vexpress-a9/drivers/board.c
@@ -19,9 +19,13 @@
 
 #define SYS_CTRL                        __REG32(REALVIEW_SCTL_BASE)
 
-extern void idle_wfi(void);
 extern void rt_hw_ipi_handler_install(int ipi_vector, rt_isr_handler_t ipi_isr_handler);
 
+void idle_wfi(void)
+{
+    asm volatile ("wfi");
+}
+
 /**
  * This function will initialize beaglebone board
  */
@@ -42,4 +46,3 @@ void rt_hw_board_init(void)
     rt_hw_ipi_handler_install(RT_SCHEDULE_IPI, rt_scheduler_ipi_handler);
 #endif
 }
-