背景
近期开始学习嵌入式开发，选择的是STM32MP157-D开发板，根据网上的教程，在学习ST官方u-boot 2022.10时发现启动流程与网上的教程不一致。
u-boot.lds
/* SPDX-License-Identifier: GPL-2.0+ */
/*
* Copyright (c) 2004-2008 Texas Instruments
*
* (C) Copyright 2002
* Gary Jennejohn, DENX Software Engineering, <[email]garyj@denx.de[/email]>
*/
#include <config.h>
#include <asm/psci.h>
OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
OUTPUT_ARCH(arm)
ENTRY(_start)
SECTIONS
{
#ifndef CONFIG_CMDLINE
/DISCARD/ : { *(__u_boot_list_2_cmd_*) }
#endif
#if defined(CONFIG_ARMV7_SECURE_BASE) && defined(CONFIG_ARMV7_NONSEC)
/*
* If CONFIG_ARMV7_SECURE_BASE is true, secure code will not
* bundle with u-boot, and code offsets are fixed. Secure zone
* only needs to be copied from the loading address to
* CONFIG_ARMV7_SECURE_BASE, which is the linking and running
* address for secure code.
*
* If CONFIG_ARMV7_SECURE_BASE is undefined, the secure zone will
* be included in u-boot address space, and some absolute address
* were used in secure code. The absolute addresses of the secure
* code also needs to be relocated along with the accompanying u-boot
* code.
*
* So DISCARD is only for CONFIG_ARMV7_SECURE_BASE.
*/
/DISCARD/ : { *(.rel._secure*) }
#endif
. = 0x00000000;
. = ALIGN(4);
.text :
{
*(.__image_copy_start)
*(.vectors)
CPUDIR/start.o (.text*)
}
/* This needs to come before *(.text*) */
.__efi_runtime_start : {
*(.__efi_runtime_start)
}
.efi_runtime : {
*(.text.efi_runtime*)
*(.rodata.efi_runtime*)
*(.data.efi_runtime*)
}
.__efi_runtime_stop : {
*(.__efi_runtime_stop)
}
.text_rest :
{
*(.text*)
}
#ifdef CONFIG_ARMV7_NONSEC
/* Align the secure section only if we're going to use it in situ */
.__secure_start
#ifndef CONFIG_ARMV7_SECURE_BASE
ALIGN(CONSTANT(COMMONPAGESIZE))
#endif
: {
KEEP(*(.__secure_start))
}
#ifndef CONFIG_ARMV7_SECURE_BASE
#define CONFIG_ARMV7_SECURE_BASE
#define __ARMV7_PSCI_STACK_IN_RAM
#endif
.secure_text CONFIG_ARMV7_SECURE_BASE :
AT(ADDR(.__secure_start) + SIZEOF(.__secure_start))
{
*(._secure.text)
}
.secure_data : AT(LOADADDR(.secure_text) + SIZEOF(.secure_text))
{
*(._secure.data)
}
#ifdef CONFIG_ARMV7_PSCI
.secure_stack ALIGN(ADDR(.secure_data) + SIZEOF(.secure_data),
CONSTANT(COMMONPAGESIZE)) (NOLOAD) :
#ifdef __ARMV7_PSCI_STACK_IN_RAM
AT(ADDR(.secure_stack))
#else
AT(LOADADDR(.secure_data) + SIZEOF(.secure_data))
#endif
{
KEEP(*(.__secure_stack_start))
/* Skip addreses for stack */
. = . + CONFIG_ARMV7_PSCI_NR_CPUS * ARM_PSCI_STACK_SIZE;
/* Align end of stack section to page boundary */
. = ALIGN(CONSTANT(COMMONPAGESIZE));
KEEP(*(.__secure_stack_end))
#ifdef CONFIG_ARMV7_SECURE_MAX_SIZE
/*
* We are not checking (__secure_end - __secure_start) here,
* as these are the load addresses, and do not include the
* stack section. Instead, use the end of the stack section
* and the start of the text section.
*/
ASSERT((. - ADDR(.secure_text)) <= CONFIG_ARMV7_SECURE_MAX_SIZE,
"Error: secure section exceeds secure memory size");
#endif
}
#ifndef __ARMV7_PSCI_STACK_IN_RAM
/* Reset VMA but don't allocate space if we have secure SRAM */
. = LOADADDR(.secure_stack);
#endif
#endif
.__secure_end : AT(ADDR(.__secure_end)) {
*(.__secure_end)
LONG(0x1d1071c); /* Must output something to reset LMA */
}
#endif
. = ALIGN(4);
.rodata : { *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*))) }
. = ALIGN(4);
.data : {
*(.data*)
}
. = ALIGN(4);
. = .;
. = ALIGN(4);
__u_boot_list : {
KEEP(*(SORT(__u_boot_list*)));
}
. = ALIGN(4);
.efi_runtime_rel_start :
{
*(.__efi_runtime_rel_start)
}
.efi_runtime_rel : {
*(.rel*.efi_runtime)
*(.rel*.efi_runtime.*)
}
.efi_runtime_rel_stop :
{
*(.__efi_runtime_rel_stop)
}
. = ALIGN(4);
.image_copy_end :
{
*(.__image_copy_end)
}
.rel_dyn_start :
{
*(.__rel_dyn_start)
}
.rel.dyn : {
*(.rel*)
}
.rel_dyn_end :
{
*(.__rel_dyn_end)
}
.end :
{
*(.__end)
}
_image_binary_end = .;
/*
* Deprecated: this MMU section is used by pxa at present but
* should not be used by new boards/CPUs.
*/
. = ALIGN(4096);
.mmutable : {
*(.mmutable)
}
/*
* Compiler-generated __bss_start and __bss_end, see arch/arm/lib/bss.c
* __bss_base and __bss_limit are for linker only (overlay ordering)
*/
.bss_start __rel_dyn_start (OVERLAY) : {
KEEP(*(.__bss_start));
__bss_base = .;
}
.bss __bss_base (OVERLAY) : {
*(.bss*)
. = ALIGN(4);
__bss_limit = .;
}
.bss_end __bss_limit (OVERLAY) : {
KEEP(*(.__bss_end));
}
.dynsym _image_binary_end : { *(.dynsym) }
.dynbss : { *(.dynbss) }
.dynstr : { *(.dynstr*) }
.dynamic : { *(.dynamic*) }
.plt : { *(.plt*) }
.interp : { *(.interp*) }
.gnu.hash : { *(.gnu.hash) }
.gnu : { *(.gnu*) }
.ARM.exidx : { *(.ARM.exidx*) }
.gnu.linkonce.armexidx : { *(.gnu.linkonce.armexidx.*) }
}
通过ENTRY确定入口为_start
vectors.S
根据网上的教程，确认_start在vectors.S文件，文件内容如下：
/* SPDX-License-Identifier: GPL-2.0+ */
/*
* vectors - Generic ARM exception table code
*
* Copyright (c) 1998 Dan Malek <[email]dmalek@jlc.net[/email]>
* Copyright (c) 1999 Magnus Damm <kieraypc01.p.y.kie.era.ericsson.se>
* Copyright (c) 2000 Wolfgang Denk <[email]wd@denx.de[/email]>
* Copyright (c) 2001 Alex Züpke <[email]azu@sysgo.de[/email]>
* Copyright (c) 2001 Marius Gröger <[email]mag@sysgo.de[/email]>
* Copyright (c) 2002 Alex Züpke <[email]azu@sysgo.de[/email]>
* Copyright (c) 2002 Gary Jennejohn <[email]garyj@denx.de[/email]>
* Copyright (c) 2002 Kyle Harris <[email]kharris@nexus-tech.net[/email]>
*/
#include <config.h>
/*
* A macro to allow insertion of an ARM exception vector either
* for the non-boot0 case or by a boot0-header.
*/
.macro ARM_VECTORS
#ifdef CONFIG_ARCH_K3
ldr pc, _reset
#else
b reset
#endif
#if !CONFIG_IS_ENABLED(SYS_NO_VECTOR_TABLE)
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
#endif
.endm
/*
*************************************************************************
*
* Symbol _start is referenced elsewhere, so make it global
*
*************************************************************************
*/
.globl _start
/*
*************************************************************************
*
* Vectors have their own section so linker script can map them easily
*
*************************************************************************
*/
.section ".vectors", "ax"
#if defined(CONFIG_ENABLE_ARM_SOC_BOOT0_HOOK)
/*
* Various SoCs need something special and SoC-specific up front in
* order to boot, allow them to set that in their boot0.h file and then
* use it here.
*
* To allow a boot0 hook to insert a 'special' sequence after the vector
* table (e.g. for the socfpga), the presence of a boot0 hook supresses
* the below vector table and assumes that the vector table is filled in
* by the boot0 hook. The requirements for a boot0 hook thus are:
* (1) defines '_start:' as appropriate
* (2) inserts the vector table using ARM_VECTORS as appropriate
*/
#include <asm/arch/boot0.h>
#else
/*
*************************************************************************
*
* Exception vectors as described in ARM reference manuals
*
* Uses indirect branch to allow reaching handlers anywhere in memory.
*
*************************************************************************
*/
_start:
#ifdef CONFIG_SYS_DV_NOR_BOOT_CFG
.word CONFIG_SYS_DV_NOR_BOOT_CFG
#endif
ARM_VECTORS
#endif /* !defined(CONFIG_ENABLE_ARM_SOC_BOOT0_HOOK) */
#if !CONFIG_IS_ENABLED(SYS_NO_VECTOR_TABLE)
/*
*************************************************************************
*
* Indirect vectors table
*
* Symbols referenced here must be defined somewhere else
*
*************************************************************************
*/
.globl _reset
.globl _undefined_instruction
.globl _software_interrupt
.globl _prefetch_abort
.globl _data_abort
.globl _not_used
.globl _irq
.globl _fiq
#ifdef CONFIG_ARCH_K3
_reset: .word reset
#endif
_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
.balignl 16,0xdeadbeef
#endif
/*
*************************************************************************
*
* Interrupt handling
*
*************************************************************************
*/
/* SPL interrupt handling: just hang */
#ifdef CONFIG_SPL_BUILD
#if !CONFIG_IS_ENABLED(SYS_NO_VECTOR_TABLE)
.align 5
undefined_instruction:
software_interrupt:
prefetch_abort:
data_abort:
not_used:
irq:
fiq:
1:
b 1b /* hang and never return */
#endif
#else /* !CONFIG_SPL_BUILD */
/* IRQ stack memory (calculated at run-time) + 8 bytes */
.globl IRQ_STACK_START_IN
IRQ_STACK_START_IN:
#ifdef IRAM_BASE_ADDR
.word IRAM_BASE_ADDR + 0x20
#else
.word 0x0badc0de
#endif
@
@ IRQ stack frame.
@
#define S_FRAME_SIZE 72
#define S_OLD_R0 68
#define S_PSR 64
#define S_PC 60
#define S_LR 56
#define S_SP 52
#define S_IP 48
#define S_FP 44
#define S_R10 40
#define S_R9 36
#define S_R8 32
#define S_R7 28
#define S_R6 24
#define S_R5 20
#define S_R4 16
#define S_R3 12
#define S_R2 8
#define S_R1 4
#define S_R0 0
#define MODE_SVC 0x13
#define I_BIT 0x80
/*
* use bad_save_user_regs for abort/prefetch/undef/swi ...
* use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
*/
.macro bad_save_user_regs
@ carve out a frame on current user stack
sub sp, sp, #S_FRAME_SIZE
stmia sp, {r0 - r12} @ Save user registers (now in svc mode) r0-r12
ldr r2, IRQ_STACK_START_IN
@ get values for "aborted" pc and cpsr (into parm regs)
ldmia r2, {r2 - r3}
add r0, sp, #S_FRAME_SIZE @ grab pointer to old stack
add r5, sp, #S_SP
mov r1, lr
stmia r5, {r0 - r3} @ save sp_SVC, lr_SVC, pc, cpsr
mov r0, sp @ save current stack into r0 (param register)
.endm
.macro irq_save_user_regs
sub sp, sp, #S_FRAME_SIZE
stmia sp, {r0 - r12} @ Calling r0-r12
@ !!!! R8 NEEDS to be saved !!!! a reserved stack spot would be good.
add r8, sp, #S_PC
stmdb r8, {sp, lr}^ @ Calling SP, LR
str lr, [r8, #0] @ Save calling PC
mrs r6, spsr
str r6, [r8, #4] @ Save CPSR
str r0, [r8, #8] @ Save OLD_R0
mov r0, sp
.endm
.macro irq_restore_user_regs
ldmia sp, {r0 - lr}^ @ Calling r0 - lr
mov r0, r0
ldr lr, [sp, #S_PC] @ Get PC
add sp, sp, #S_FRAME_SIZE
subs pc, lr, #4 @ return & move spsr_svc into cpsr
.endm
.macro get_bad_stack
ldr r13, IRQ_STACK_START_IN @ setup our mode stack
str lr, [r13] @ save caller lr in position 0 of saved stack
mrs lr, spsr @ get the spsr
str lr, [r13, #4] @ save spsr in position 1 of saved stack
mov r13, #MODE_SVC @ prepare SVC-Mode
@ msr spsr_c, r13
msr spsr, r13 @ switch modes, make sure moves will execute
mov lr, pc @ capture return pc
movs pc, lr @ jump to next instruction & switch modes.
.endm
.macro get_irq_stack @ setup IRQ stack
ldr sp, IRQ_STACK_START
.endm
.macro get_fiq_stack @ setup FIQ stack
ldr sp, FIQ_STACK_START
.endm
/*
* exception handlers
*/
.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
.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 /* CONFIG_SPL_BUILD */
根据网上的代码，在_start处缺少了b reset
start.S
xxx
/* SPDX-License-Identifier: GPL-2.0+ */
/*
* armboot - Startup Code for OMAP3530/ARM Cortex CPU-core
*
* Copyright (c) 2004 Texas Instruments <[email]r-woodruff2@ti.com[/email]>
*
* Copyright (c) 2001 Marius Gröger <[email]mag@sysgo.de[/email]>
* Copyright (c) 2002 Alex Züpke <[email]azu@sysgo.de[/email]>
* Copyright (c) 2002 Gary Jennejohn <[email]garyj@denx.de[/email]>
* Copyright (c) 2003 Richard Woodruff <[email]r-woodruff2@ti.com[/email]>
* Copyright (c) 2003 Kshitij <[email]kshitij@ti.com[/email]>
* Copyright (c) 2006-2008 Syed Mohammed Khasim <[email]x0khasim@ti.com[/email]>
*/
#include <asm-offsets.h>
#include <config.h>
#include <asm/system.h>
#include <linux/linkage.h>
#include <asm/armv7.h>
#include <system-constants.h>
/*************************************************************************
*
* 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 reset
.globl save_boot_params_ret
.type save_boot_params_ret,%function
#ifdef CONFIG_ARMV7_LPAE
.global switch_to_hypervisor_ret
#endif
reset:
/* Allow the board to save important registers */
b save_boot_params
save_boot_params_ret:
#ifdef CONFIG_POSITION_INDEPENDENT
/*
* Fix .rela.dyn relocations. This allows U-Boot to loaded to and
* executed at a different address than it was linked at.
*/
pie_fixup:
adr r0, reset /* r0 <- Runtime value of reset label */
ldr r1, =reset /* r1 <- Linked value of reset label */
subs r4, r0, r1 /* r4 <- Runtime-vs-link offset */
beq pie_fixup_done
adr r0, pie_fixup
ldr r1, _rel_dyn_start_ofs
add r2, r0, r1 /* r2 <- Runtime &__rel_dyn_start */
ldr r1, _rel_dyn_end_ofs
add r3, r0, r1 /* r3 <- Runtime &__rel_dyn_end */
pie_fix_loop:
ldr r0, [r2] /* r0 <- Link location */
ldr r1, [r2, #4] /* r1 <- fixup */
cmp r1, #23 /* relative fixup? */
bne pie_skip_reloc
/* relative fix: increase location by offset */
add r0, r4
ldr r1, [r0]
add r1, r4
str r1, [r0]
str r0, [r2]
add r2, #8
pie_skip_reloc:
cmp r2, r3
blo pie_fix_loop
pie_fixup_done:
#endif
#ifdef CONFIG_ARMV7_LPAE
/*
* check for Hypervisor support
*/
mrc p15, 0, r0, c0, c1, 1 @ read ID_PFR1
and r0, r0, #CPUID_ARM_VIRT_MASK @ mask virtualization bits
cmp r0, #(1 << CPUID_ARM_VIRT_SHIFT)
beq switch_to_hypervisor
switch_to_hypervisor_ret:
#endif
/*
* disable interrupts (FIQ and IRQ), also set the cpu to SVC32 mode,
* except if in HYP mode already
*/
mrs r0, cpsr
and r1, r0, #0x1f @ mask mode bits
teq r1, #0x1a @ test for HYP mode
bicne r0, r0, #0x1f @ clear all mode bits
orrne r0, r0, #0x13 @ set SVC mode
orr r0, r0, #0xc0 @ disable FIQ and IRQ
msr cpsr,r0
#if !CONFIG_IS_ENABLED(SYS_NO_VECTOR_TABLE)
/*
* Setup vector:
*/
/* Set V=0 in CP15 SCTLR register - for VBAR to point to vector */
mrc p15, 0, r0, c1, c0, 0 @ Read CP15 SCTLR Register
bic r0, #CR_V @ V = 0
mcr p15, 0, r0, c1, c0, 0 @ Write CP15 SCTLR Register
#ifdef CONFIG_HAS_VBAR
/* Set vector address in CP15 VBAR register */
ldr r0, =_start
mcr p15, 0, r0, c12, c0, 0 @Set VBAR
#endif
#endif
/* the mask ROM code should have PLL and others stable */
#if !CONFIG_IS_ENABLED(SKIP_LOWLEVEL_INIT)
#ifdef CONFIG_CPU_V7A
bl cpu_init_cp15
#endif
#if !CONFIG_IS_ENABLED(SKIP_LOWLEVEL_INIT_ONLY)
bl cpu_init_crit
#endif
#endif
bl _main
/*------------------------------------------------------------------------------*/
ENTRY(c_runtime_cpu_setup)
/*
* If I-cache is enabled invalidate it
*/
#if !CONFIG_IS_ENABLED(SYS_ICACHE_OFF)
mcr p15, 0, r0, c7, c5, 0 @ invalidate icache
mcr p15, 0, r0, c7, c10, 4 @ DSB
mcr p15, 0, r0, c7, c5, 4 @ ISB
#endif
bx lr
ENDPROC(c_runtime_cpu_setup)
/*************************************************************************
*
* void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3)
* __attribute__((weak));
*
* Stack pointer is not yet initialized at this moment
* Don't save anything to stack even if compiled with -O0
*
*************************************************************************/
ENTRY(save_boot_params)
b save_boot_params_ret @ back to my caller
ENDPROC(save_boot_params)
.weak save_boot_params
#ifdef CONFIG_ARMV7_LPAE
ENTRY(switch_to_hypervisor)
b switch_to_hypervisor_ret
ENDPROC(switch_to_hypervisor)
.weak switch_to_hypervisor
#endif
/*************************************************************************
*
* cpu_init_cp15
*
* Setup CP15 registers (cache, MMU, TLBs). The I-cache is turned on unless
* CONFIG_SYS_ICACHE_OFF is defined.
*
*************************************************************************/
ENTRY(cpu_init_cp15)
#if CONFIG_IS_ENABLED(ARMV7_SET_CORTEX_SMPEN)
/*
* The Arm Cortex-A7 TRM says this bit must be enabled before
* "any cache or TLB maintenance operations are performed".
*/
mrc p15, 0, r0, c1, c0, 1 @ read auxilary control register
orr r0, r0, #1 << 6 @ set SMP bit to enable coherency
mcr p15, 0, r0, c1, c0, 1 @ write auxilary control register
#endif
/*
* Invalidate L1 I/D
*/
mov r0, #0 @ set up for MCR
mcr p15, 0, r0, c8, c7, 0 @ invalidate TLBs
mcr p15, 0, r0, c7, c5, 0 @ invalidate icache
mcr p15, 0, r0, c7, c5, 6 @ invalidate BP array
mcr p15, 0, r0, c7, c10, 4 @ DSB
mcr p15, 0, r0, c7, c5, 4 @ ISB
/*
* disable MMU stuff and caches
*/
mrc p15, 0, r0, c1, c0, 0
bic r0, r0, #0x00002000 @ clear bits 13 (--V-)
bic r0, r0, #0x00000007 @ clear bits 2:0 (-CAM)
orr r0, r0, #0x00000002 @ set bit 1 (--A-) Align
orr r0, r0, #0x00000800 @ set bit 11 (Z---) BTB
#if CONFIG_IS_ENABLED(SYS_ICACHE_OFF)
bic r0, r0, #0x00001000 @ clear bit 12 (I) I-cache
#else
orr r0, r0, #0x00001000 @ set bit 12 (I) I-cache
#endif
mcr p15, 0, r0, c1, c0, 0
#ifdef CONFIG_ARM_ERRATA_716044
mrc p15, 0, r0, c1, c0, 0 @ read system control register
orr r0, r0, #1 << 11 @ set bit #11
mcr p15, 0, r0, c1, c0, 0 @ write system control register
#endif
#if (defined(CONFIG_ARM_ERRATA_742230) || defined(CONFIG_ARM_ERRATA_794072))
mrc p15, 0, r0, c15, c0, 1 @ read diagnostic register
orr r0, r0, #1 << 4 @ set bit #4
mcr p15, 0, r0, c15, c0, 1 @ write diagnostic register
#endif
#ifdef CONFIG_ARM_ERRATA_743622
mrc p15, 0, r0, c15, c0, 1 @ read diagnostic register
orr r0, r0, #1 << 6 @ set bit #6
mcr p15, 0, r0, c15, c0, 1 @ write diagnostic register
#endif
#ifdef CONFIG_ARM_ERRATA_751472
mrc p15, 0, r0, c15, c0, 1 @ read diagnostic register
orr r0, r0, #1 << 11 @ set bit #11
mcr p15, 0, r0, c15, c0, 1 @ write diagnostic register
#endif
#ifdef CONFIG_ARM_ERRATA_761320
mrc p15, 0, r0, c15, c0, 1 @ read diagnostic register
orr r0, r0, #1 << 21 @ set bit #21
mcr p15, 0, r0, c15, c0, 1 @ write diagnostic register
#endif
#ifdef CONFIG_ARM_ERRATA_845369
mrc p15, 0, r0, c15, c0, 1 @ read diagnostic register
orr r0, r0, #1 << 22 @ set bit #22
mcr p15, 0, r0, c15, c0, 1 @ write diagnostic register
#endif
mov r5, lr @ Store my Caller
mrc p15, 0, r1, c0, c0, 0 @ r1 has Read Main ID Register (MIDR)
mov r3, r1, lsr #20 @ get variant field
and r3, r3, #0xf @ r3 has CPU variant
and r4, r1, #0xf @ r4 has CPU revision
mov r2, r3, lsl #4 @ shift variant field for combined value
orr r2, r4, r2 @ r2 has combined CPU variant + revision
/* Early stack for ERRATA that needs into call C code */
#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
ldr r0, =(CONFIG_SPL_STACK)
#else
ldr r0, =(SYS_INIT_SP_ADDR)
#endif
bic r0, r0, #7 /* 8-byte alignment for ABI compliance */
mov sp, r0
#ifdef CONFIG_ARM_ERRATA_798870
cmp r2, #0x30 @ Applies to lower than R3p0
bge skip_errata_798870 @ skip if not affected rev
cmp r2, #0x20 @ Applies to including and above R2p0
blt skip_errata_798870 @ skip if not affected rev
mrc p15, 1, r0, c15, c0, 0 @ read l2 aux ctrl reg
orr r0, r0, #1 << 7 @ Enable hazard-detect timeout
push {r1-r5} @ Save the cpu info registers
bl v7_arch_cp15_set_l2aux_ctrl
isb @ Recommended ISB after l2actlr update
pop {r1-r5} @ Restore the cpu info - fall through
skip_errata_798870:
#endif
#ifdef CONFIG_ARM_ERRATA_801819
cmp r2, #0x24 @ Applies to lt including R2p4
bgt skip_errata_801819 @ skip if not affected rev
cmp r2, #0x20 @ Applies to including and above R2p0
blt skip_errata_801819 @ skip if not affected rev
mrc p15, 0, r0, c0, c0, 6 @ pick up REVIDR reg
and r0, r0, #1 << 3 @ check REVIDR[3]
cmp r0, #1 << 3
beq skip_errata_801819 @ skip erratum if REVIDR[3] is set
mrc p15, 0, r0, c1, c0, 1 @ read auxilary control register
orr r0, r0, #3 << 27 @ Disables streaming. All write-allocate
@ lines allocate in the L1 or L2 cache.
orr r0, r0, #3 << 25 @ Disables streaming. All write-allocate
@ lines allocate in the L1 cache.
push {r1-r5} @ Save the cpu info registers
bl v7_arch_cp15_set_acr
pop {r1-r5} @ Restore the cpu info - fall through
skip_errata_801819:
#endif
#ifdef CONFIG_ARM_CORTEX_A15_CVE_2017_5715
mrc p15, 0, r0, c1, c0, 1 @ read auxilary control register
orr r0, r0, #1 << 0 @ Enable invalidates of BTB
push {r1-r5} @ Save the cpu info registers
bl v7_arch_cp15_set_acr
pop {r1-r5} @ Restore the cpu info - fall through
#endif
#ifdef CONFIG_ARM_ERRATA_454179
mrc p15, 0, r0, c1, c0, 1 @ Read ACR
cmp r2, #0x21 @ Only on < r2p1
orrlt r0, r0, #(0x3 << 6) @ Set DBSM(BIT7) and IBE(BIT6) bits
push {r1-r5} @ Save the cpu info registers
bl v7_arch_cp15_set_acr
pop {r1-r5} @ Restore the cpu info - fall through
#endif
#if defined(CONFIG_ARM_ERRATA_430973) || defined (CONFIG_ARM_CORTEX_A8_CVE_2017_5715)
mrc p15, 0, r0, c1, c0, 1 @ Read ACR
#ifdef CONFIG_ARM_CORTEX_A8_CVE_2017_5715
orr r0, r0, #(0x1 << 6) @ Set IBE bit always to enable OS WA
#else
cmp r2, #0x21 @ Only on < r2p1
orrlt r0, r0, #(0x1 << 6) @ Set IBE bit
#endif
push {r1-r5} @ Save the cpu info registers
bl v7_arch_cp15_set_acr
pop {r1-r5} @ Restore the cpu info - fall through
#endif
#ifdef CONFIG_ARM_ERRATA_621766
mrc p15, 0, r0, c1, c0, 1 @ Read ACR
cmp r2, #0x21 @ Only on < r2p1
orrlt r0, r0, #(0x1 << 5) @ Set L1NEON bit
push {r1-r5} @ Save the cpu info registers
bl v7_arch_cp15_set_acr
pop {r1-r5} @ Restore the cpu info - fall through
#endif
#ifdef CONFIG_ARM_ERRATA_725233
mrc p15, 1, r0, c9, c0, 2 @ Read L2ACR
cmp r2, #0x21 @ Only on < r2p1 (Cortex A8)
orrlt r0, r0, #(0x1 << 27) @ L2 PLD data forwarding disable
push {r1-r5} @ Save the cpu info registers
bl v7_arch_cp15_set_l2aux_ctrl
pop {r1-r5} @ Restore the cpu info - fall through
#endif
#ifdef CONFIG_ARM_ERRATA_852421
mrc p15, 0, r0, c15, c0, 1 @ read diagnostic register
orr r0, r0, #1 << 24 @ set bit #24
mcr p15, 0, r0, c15, c0, 1 @ write diagnostic register
#endif
#ifdef CONFIG_ARM_ERRATA_852423
mrc p15, 0, r0, c15, c0, 1 @ read diagnostic register
orr r0, r0, #1 << 12 @ set bit #12
mcr p15, 0, r0, c15, c0, 1 @ write diagnostic register
#endif
mov pc, r5 @ back to my caller
ENDPROC(cpu_init_cp15)
#if !CONFIG_IS_ENABLED(SKIP_LOWLEVEL_INIT) && \
!CONFIG_IS_ENABLED(SKIP_LOWLEVEL_INIT_ONLY)
/*************************************************************************
*
* CPU_init_critical registers
*
* setup important registers
* setup memory timing
*
*************************************************************************/
ENTRY(cpu_init_crit)
/*
* Jump to board specific initialization...
* The Mask ROM will have already initialized
* basic memory. Go here to bump up clock rate and handle
* wake up conditions.
*/
b lowlevel_init @ go setup pll,mux,memory
ENDPROC(cpu_init_crit)
#endif
#if CONFIG_POSITION_INDEPENDENT
_rel_dyn_start_ofs:
.word __rel_dyn_start - pie_fixup
_rel_dyn_end_ofs:
.word __rel_dyn_end - pie_fixup
#endif
正确启动流程是什么样的，谁能够帮忙梳理下，多谢😄
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可以使用GDB追踪。 GDB - stm32mpu (stmicroelectronics.cn)
您好!
不知道下面的链接的内容能不能帮到您！
https://gitee.com/qingbicui/only_scratch_the_surface-stm32mp1-study_notes