board_init_f 分析（六）
当cpu_init_crit 初始化完毕后，会顺序执行到call_board_init_f的地方。
/* Set stackpointer in internal RAM to call board_init_f */
call_board_init_f:
ldr sp, =(CONFIG_SYS_INIT_SP_ADDR)
bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
ldr r0,=0x00000000
#if defined(CONFIG_CARL210) || defined(CONFIG_MINI210)
adr r4, _start
ldr r5,_TEXT_BASE
cmp r5,r4
beq board_init_in_ram
ldr r0, =PRO_ID_BASE
ldr r1, [r0,#OMR_OFFSET]
bic r2, r1, #0xffffffc1
/* NAND BOOT */
cmp r2, #0x0 @ 512B 4-cycle
moveq r3, #BOOT_NAND
cmp r2, #0x2 @ 2KB 5-cycle
moveq r3, #BOOT_NAND
cmp r2, #0x4 @ 4KB 5-cycle 8-bit ECC
moveq r3, #BOOT_NAND
cmp r2, #0x6 @ 4KB 5-cycle 16-bit ECC
moveq r3, #BOOT_NAND
cmp r2, #0x8 @ OneNAND Mux
moveq r3, #BOOT_ONENAND
/* SD/MMC BOOT */
cmp r2, #0xc
moveq r3, #BOOT_MMCSD
/* NOR BOOT */
cmp r2, #0x14
moveq r3, #BOOT_NOR
/* Uart BOOTONG failed */
cmp r2, #(0x1<<4)
moveq r3, #BOOT_SEC_DEV
ldr r0, =INF_REG_BASE
str r3, [r0, #INF_REG3_OFFSET]
ldr r1, [r0, #INF_REG3_OFFSET]
cmp r1, #BOOT_NAND /* 0x0 => boot device is nand */
beq nand_boot_210
cmp r1, #BOOT_MMCSD
beq mmcsd_boot_210
nand_boot_210:
bl board_init_f_nand
mmcsd_boot_210:
bl board_init_f
board_init_in_ram:
#endif
bl board_init_fvoid board_init_f(ulong bootflag)
{
bd_t *bd;
init_fnc_t **init_fnc_ptr;
gd_t *id;
ulong addr, addr_sp;
/* Pointer is writable since we allocated a register for it */
gd = (gd_t *) ((CONFIG_SYS_INIT_SP_ADDR) & ~0x07);
/* compiler optimization barrier needed for GCC >= 3.4 */
__asm__ __volatile__("": : :"memory");
memset((void *)gd, 0, sizeof(gd_t));最重要的是gd这个全局的变量，记录着整个系统启动的关键属性，申请空间后初始化为0
for (init_fnc_ptr = init_sequence; *init_fnc_ptr; ++init_fnc_ptr) {
if ((*init_fnc_ptr)() != 0) {
hang ();
}
}函数指针，其定义是
init_fnc_t *init_sequence[] = {
#if defined(CONFIG_ARCH_CPU_INIT)
arch_cpu_init, /* basic arch cpu dependent setup */
#endif
#if defined(CONFIG_BOARD_EARLY_INIT_F)
board_early_init_f,
#endif
timer_init, /* initialize timer */
#ifdef CONFIG_FSL_ESDHC
get_clocks,
#endif
env_init, /* initialize environment */
init_baudrate, /* initialze baudrate settings */
serial_init, /* serial communications setup */
console_init_f, /* stage 1 init of console */
display_banner, /* say that we are here */
#if defined(CONFIG_DISPLAY_CPUINFO)
print_cpuinfo, /* display cpu info (and speed) */
#endif
#if defined(CONFIG_DISPLAY_BOARDINFO)
checkboard, /* display board info */
#endif
#if defined(CONFIG_HARD_I2C) || defined(CONFIG_SOFT_I2C)
init_func_i2c,
#endif
dram_init, /* configure available RAM banks */
NULL,
};relocate_code(addr_sp, id, addr);这个将addr_sp，id ，addr 传入参数，跳转到了start.S
relocate_code:
mov r4, r0 /* save addr_sp */
mov r5, r1 /* save addr of gd */
mov r6, r2 /* save addr of destination */
/* Set up the stack */
stack_setup:
mov sp, r4
adr r0, _start
cmp r0, r6
moveq r9, #0 /* no relocation. relocation offset(r9) = 0 */
beq clear_bss /* skip relocation */
mov r1, r6 /* r1 <- scratch for copy_loop */
ldr r3, _image_copy_end_ofs
add r2, r0, r3 /* r2 <- source end address */
copy_loop:
ldmia r0!, {r9-r10} /* copy from source address [r0] */
stmia r1!, {r9-r10} /* copy to target address [r1] */
cmp r0, r2 /* until source end address [r2] */
blo copy_loop
/////////////////////////////////////////////////////////////////////////////////
#ifndef CONFIG_SPL_BUILD
/*
* fix .rel.dyn relocations
*/
ldr r0, _TEXT_BASE /* r0 <- Text base */
sub r9, r6, r0 /* r9 <- relocation offset */
ldr r10, _dynsym_start_ofs /* r10 <- sym table ofs */
add r10, r10, r0 /* r10 <- sym table in FLASH */
ldr r2, _rel_dyn_start_ofs /* r2 <- rel dyn start ofs */
add r2, r2, r0 /* r2 <- rel dyn start in FLASH */
ldr r3, _rel_dyn_end_ofs /* r3 <- rel dyn end ofs */
add r3, r3, r0 /* r3 <- rel dyn end in FLASH */
fixloop:
ldr r0, [r2] /* r0 <- location to fix up, IN FLASH! */
add r0, r0, r9 /* r0 <- location to fix up in RAM */
ldr r1, [r2, #4]
and r7, r1, #0xff
cmp r7, #23 /* relative fixup? */
beq fixrel
cmp r7, #2 /* absolute fixup? */
beq fixabs
/* ignore unknown type of fixup */
b fixnext
fixabs:
/*
*/
/* absolute fix: set location to (offset) symbol value */
mov r1, r1, LSR #4 /* r1 <- symbol index in .dynsym */
add r1, r10, r1 /* r1 <- address of symbol in table */
ldr r1, [r1, #4] /* r1 <- symbol value */
add r1, r1, r9 /* r1 <- relocated sym addr */
b fixnext
fixrel:
/* relative fix: increase location by offset */
ldr r1, [r0]
add r1, r1, r9
fixnext:
str r1, [r0]
add r2, r2, #8 /* each rel.dyn entry is 8 bytes */
cmp r2, r3
blo fixloop
b clear_bss
_rel_dyn_start_ofs:
.word __rel_dyn_start - _start
_rel_dyn_end_ofs:
.word __rel_dyn_end - _start
_dynsym_start_ofs:
.word __dynsym_start - _start
#endif /* #ifndef CONFIG_SPL_BUILD */
/////////////////////////////////////////////////////////////////////////////////////
clear_bss:
#ifdef CONFIG_SPL_BUILD
/* No relocation for SPL */
ldr r0, =__bss_start
ldr r1, =__bss_end__
#else
ldr r0, _bss_start_ofs
ldr r1, _bss_end_ofs
mov r4, r6 /* reloc addr */
add r0, r0, r4
add r1, r1, r4
#endif
mov r2, #0x00000000 /* clear */
clbss_l:str r2, [r0] /* clear loop... */
add r0, r0, #4
cmp r0, r1
bne clbss_l
/*
* We are done. Do not return, instead branch to second part of board
* initialization, now running from RAM.
*/
jump_2_ram:
/*
* If I-cache is enabled invalidate it
*/
#ifndef CONFIG_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
ldr r0, _board_init_r_ofs
adr r1, _start
add lr, r0, r1
add lr, lr, r9
/* setup parameters for board_init_r */
mov r0, r5 /* gd_t */
mov r1, r6 /* dest_addr */
/* jump to it ... */
mov pc, lr
这中间将mmc上的代码拷贝到ram中后，跳转到board_init_r函数中Board.c (arch\arm\lib)