Arm Development Studio forum how to invoke arm cortex m3 pendsv handle

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how to invoke arm cortex m3 pendsv handle

Note: This was originally posted on 4th September 2013 at http://forums.arm.com

I try to invoke pendsv handle after svc. I can enter svc_isr, but after exit svc_isr, can not enter pendsv_handle, direct go to deadloop.
Can not go to pendsv_handle.

dump 0xe000ed04

(gdb) x/1xw 0xe000ed04
0xe000ed04: 0x1080e000[size=2]
[/size][size=2]It looks good.[/size]
Any suggest? Thank you for your help.

environment:
gcc
stm32discovery board

my code:

# test pendSV handler

.equ STACK_TOP, 0x20000800
.text
.global _start
.code 16
.syntax unified
_start:
  .word STACK_TOP, start
  .type start, function @ let lsb to 1
  .word int_isr+1
  .word int_isr+1
  .word int_isr+1
  .word int_isr+1
  .word int_isr+1
  .word int_isr+1
  .word int_isr+1
  .word int_isr+1
  .word int_isr+1
  .word svc_isr+1 @ svc isr
  .word int_isr+1
  .word int_isr+1
  .word pendsv_handle+1
  .word int_isr+1
  .word int_isr+1
  .word int_isr+1
  .word int_isr+1

start:

@ ref: @ Cortex™-M3 Technical Reference Manual (file name: DDI0337E_cortex_m3_r1p1_trm.pdf)
@    System Handler Priority Registers (p8-27)
  @ pendsv priority
  ldr r0, =0xe000ed22
  mov r1, #0xff
  strb r1, [r0]

  @ systick priority
  ldr r0, =0xe000ed23
  mov r1, #0xff
  strb r1, [r0]

  @ svc priority
  ldr r0, =0xe000ed1f
  mov r1, #0xff
  strb r1, [r0]

  cpsie i

  svc 0

@ watch 0xe000ed24, 0xe000ed04 ref: arm cortex-m3: 嵌入式系統設計入門 p8-9

  push {r0}

deadloop:
  nop
  push {r0}
  b deadloop

pendsv_handle:
  movs r2, #0x12
  nop
  bx lr

svc_isr:
  @ enable pendsv ref: STM32F207 高性能网络型 MCU 嵌入式系统设计 p 412
  ldr r0, =0xe000ed04 
  ldr r1, [r0]
  orr r1, #0x10000000
  str r1, [r0]
  nop
  movs r3, #0x56
  bx lr

int_isr:
  nop
  movs r1, #0xf
  push {r1}
  bx lr

.data
.space  0x200, 0
psp_stack_top:

.space  0x400, 0
msp_stack_top: