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我的平臺是iMX28 + u-boot-2013.10 + Linux-3.12.10。根據我的理解，ARM異常向量應該從0x00000000開始加載到物理地址中。我的u-boot映像被加載到0x40000100，它位於DDR2內存中，iMX28的靜態RAM位於地址0x00000000中。u-boot中的異常向量地址
在start.S的代碼如下：
#ifdef CONFIG_SYS_DV_NOR_BOOT_CFG
.globl _start
_start:
.globl _NOR_BOOT_CFG
_NOR_BOOT_CFG:
.word CONFIG_SYS_DV_NOR_BOOT_CFG
b reset
#else
.globl _start
_start:
b reset
#endif
#ifdef CONFIG_SPL_BUILD
/* No exception handlers in preloader */
ldr pc, _hang
ldr pc, _hang
ldr pc, _hang
ldr pc, _hang
ldr pc, _hang
ldr pc, _hang
ldr pc, _hang
_hang:
.word do_hang
/* pad to 64 byte boundary */
.word 0x12345678
.word 0x12345678
.word 0x12345678
.word 0x12345678
.word 0x12345678
.word 0x12345678
.word 0x12345678
#else
ldr pc, _undefined_instruction
ldr pc, _software_interrupt
ldr pc, _prefetch_abort
ldr pc, _data_abort
ldr pc, _not_used
ldr pc, _irq
ldr pc, _fiq
_undefined_instruction:
.word undefined_instruction
_software_interrupt:
.word software_interrupt
_prefetch_abort:
.word prefetch_abort
_data_abort:
.word data_abort
_not_used:
.word not_used
_irq:
.word irq
_fiq:
.word fiq
#endif /* CONFIG_SPL_BUILD */
.balignl 16,0xdeadbeef
/*
*************************************************************************
*
* Startup Code (reset vector)
*
* do important init only if we don't start from memory!
* setup Memory and board specific bits prior to relocation.
* relocate armboot to ram
* setup stack
*
*************************************************************************
*/
.globl _TEXT_BASE
_TEXT_BASE:
#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_TEXT_BASE)
.word CONFIG_SPL_TEXT_BASE
#else
.word CONFIG_SYS_TEXT_BASE
#endif
/*
* These are defined in the board-specific linker script.
* Subtracting _start from them lets the linker put their
* relative position in the executable instead of leaving
* them null.
*/
.globl _bss_start_ofs
_bss_start_ofs:
.word __bss_start - _start
.globl _image_copy_end_ofs
_image_copy_end_ofs:
.word __image_copy_end - _start
.globl _bss_end_ofs
_bss_end_ofs:
.word __bss_end - _start
.globl _end_ofs
_end_ofs:
.word _end - _start
#ifdef CONFIG_USE_IRQ
/* IRQ stack memory (calculated at run-time) */
.globl IRQ_STACK_START
IRQ_STACK_START:
.word 0x0badc0de
/* IRQ stack memory (calculated at run-time) */
.globl FIQ_STACK_START
FIQ_STACK_START:
.word 0x0badc0de
#endif
/* IRQ stack memory (calculated at run-time) + 8 bytes */
.globl IRQ_STACK_START_IN
IRQ_STACK_START_IN:
.word 0x0badc0de
/*
* the actual reset code
*/
reset:
/*
* set the cpu to SVC32 mode
*/
mrs r0,cpsr
bic r0,r0,#0x1f
orr r0,r0,#0xd3
msr cpsr,r0
/*
* we do sys-critical inits only at reboot,
* not when booting from ram!
*/
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
bl cpu_init_crit
#endif
bl _main
... ...
/*
* exception handlers
*/
#ifdef CONFIG_SPL_BUILD
.align 5
do_hang:
ldr sp, _TEXT_BASE /* switch to abort stack */
1:
bl 1b /* hang and never return */
#else /* !CONFIG_SPL_BUILD */
.align 5
undefined_instruction:
get_bad_stack
bad_save_user_regs
bl do_undefined_instruction
.align 5
software_interrupt:
get_bad_stack
bad_save_user_regs
bl do_software_interrupt
.align 5
prefetch_abort:
get_bad_stack
bad_save_user_regs
bl do_prefetch_abort
.align 5
data_abort:
get_bad_stack
bad_save_user_regs
bl do_data_abort
.align 5
not_used:
get_bad_stack
bad_save_user_regs
bl do_not_used
#ifdef CONFIG_USE_IRQ
.align 5
irq:
get_irq_stack
irq_save_user_regs
bl do_irq
irq_restore_user_regs
.align 5
fiq:
get_fiq_stack
/* someone ought to write a more effiction fiq_save_user_regs */
irq_save_user_regs
bl do_fiq
irq_restore_user_regs
#else
.align 5
irq:
get_bad_stack
bad_save_user_regs
bl do_irq
.align 5
fiq:
get_bad_stack
bad_save_user_regs
bl do_fiq
#endif
#endif /* CONFIG_SPL_BUILD */
我的問題是
- 異常處理程序不在所需的地址00000000，是 是正確的？
- 如果< 1>是對的，如何將這些向量複製到 0x00000000？到現在爲止，我找不到複製 東西的代碼。
- 如果在u-boot中啓用了MMU，那麼處理程序是否成爲虛擬地址？
- 如果< 3>是正確的，是否有必要將虛擬地址轉換爲物理地址，然後將它們複製到0x00000000？
謝謝！
BR 程石
爲了回答你的問題，我們需要知道你想要做什麼知識？你只是想知道異常向量如何工作？你需要改變他們出於某種原因？爲什麼？有沒有你正在調試的問題，導致你相信你在這裏發現了問題？謝謝！ –
其實我試着在eboot中加入引用u-boot的異常處理程序。我無法理解u-boot如何實現它的異常處理程序。 – x10