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cortex-r4: let svc mode reuse the stack of IRQ on startup 

As the svc stack is the stack of threads, there is no need to allocate a
separate stack for the startup. Reuse the IRQ stack should be OK.

Tested on rm48 board.
This commit is contained in:
Grissiom 2013-11-17 12:13:25 +08:00
parent 394657979d
commit a8520ed383
1 changed files with 7 additions and 11 deletions
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18
libcpu/arm/cortex-r4/start_gcc.S
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@ -18,11 +18,10 @@
.equ F_Bit, 0x40 @ when F bit is set, FIQ is disabled
.equ UND_Stack_Size, 0x00000000
.equ SVC_Stack_Size, 0x00000100
.equ SVC_Stack_Size, 0x00000000
.equ ABT_Stack_Size, 0x00000000
.equ FIQ_Stack_Size, 0x00000000
.equ IRQ_Stack_Size, 0x00000100
.equ USR_Stack_Size, 0x00000100
.equ FIQ_Stack_Size, 0x00001000
.equ IRQ_Stack_Size, 0x00001000
.section .bss.noinit
/* stack */
@ -63,6 +62,9 @@ _reset:
@ Initialize Stack Pointers
ldr r0, =stack_top
@ Set the startup stack for svc
mov sp, r0
@ Enter Undefined Instruction Mode and set its Stack Pointer
msr cpsr_c, #Mode_UND|I_Bit|F_Bit
mov sp, r0
@ -83,14 +85,8 @@ _reset:
mov sp, r0
sub r0, r0, #IRQ_Stack_Size
@ Enter Supervisor Mode and set its Stack Pointer
@ Switch back to SVC
msr cpsr_c, #Mode_SVC|I_Bit|F_Bit
mov sp, r0
sub r0, r0, #SVC_Stack_Size
@ Enter User Mode and set its Stack Pointer
mov sp, r0
sub sl, sp, #USR_Stack_Size
bl next1
next1: