最近项目原因，要在uboot中增加内核验校和内核损坏修复功能，所以需要回头看看uboot。这次选择了uboot2015来进行分析
uboot是明远睿智提供的。
下载地址 链接：https://pan.baidu.com/s/13SuRii3WTqvFTNIsSS9GAg 密码：65zz
环境：ubuntu16
主控：imx6q
1、start.s arch\arm\cpu\armv7\start.S
因为我们这款cpu指令集是armv7的所以选择这个目录下的start.s，如果不知道自己该看那个目录下的start.s，可以用如下方法
先编译uboot，编译成功后，执行 find -name start.0 即可看见start文件所在目录
然后我们来看看代码，我对代码进行了删减，我们目的在于流程分析，就不分析具体每句话了
reset:
/* Allow the board to save important registers */
b save_boot_params
save_boot_params_ret:
/*
* disable interrupts (FIQ and IRQ), also set the cpu to SVC32 mode,
* except if in HYP mode already
*/
。。。。。。。。
/*
* Setup vector:
* (OMAP4 spl TEXT_BASE is not 32 byte aligned.
* Continue to use ROM code vector only in OMAP4 spl)
*/
#if !(defined(CONFIG_OMAP44XX) && defined(CONFIG_SPL_BUILD))
/* Set V=0 in CP15 SCTLR register - for VBAR to point to vector */
。。。。。。。。。
/* Set vector address in CP15 VBAR register */
。。。。。。。。。
#endif
/* the mask ROM code should have PLL and others stable */
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
bl cpu_init_cp15
bl cpu_init_crit
#endif
bl _main //进入_mainarch\arm\lib\crt0.S _main在这个文件里
ENTRY(_main)
/*
* Set up initial C runtime environment and call board_init_f(0).
*/
#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
ldr sp, =(CONFIG_SPL_STACK)
#else
ldr sp, =(CONFIG_SYS_INIT_SP_ADDR)
#endif
。。。。。。。
clr_gd:
。。。。。。。
#if defined(CONFIG_SYS_MALLOC_F_LEN)
sub sp, sp, #CONFIG_SYS_MALLOC_F_LEN
str sp, [r9, #GD_MALLOC_BASE]
#endif
/* mov r0, #0 not needed due to above code */
bl board_init_f /*这个函数把uboot拷贝到ram*/
#if ! defined(CONFIG_SPL_BUILD)
/*
* Set up intermediate environment (new sp and gd) and call
* relocate_code(addr_moni). Trick here is that we'll return
* 'here' but relocated.
*/
。。。。。。
b relocate_code
here:
/*
* now relocate vectors
*/
bl relocate_vectors
/* Set up final (full) environment */
bl c_runtime_cpu_setup /* we still call old routine here */
#endif
#if !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_FRAMEWORK)
# ifdef CONFIG_SPL_BUILD
/* Use a DRAM stack for the rest of SPL, if requested */
bl spl_relocate_stack_gd
cmp r0, #0
movne sp, r0
# endif
ldr r0, =__bss_start /* this is auto-relocated! */
#ifdef CONFIG_USE_ARCH_MEMSET
ldr r3, =__bss_end /* this is auto-relocated! */
mov r1, #0x00000000 /* prepare zero to clear BSS */
subs r2, r3, r0 /* r2 = memset len */
bl memset
#else
ldr r1, =__bss_end /* this is auto-relocated! */
mov r2, #0x00000000 /* prepare zero to clear BSS */
clbss_l:cmp r0, r1 /* while not at end of BSS */
strlo r2, [r0] /* clear 32-bit BSS word */
addlo r0, r0, #4 /* move to next */
blo clbss_l
#endif
#if ! defined(CONFIG_SPL_BUILD)
bl coloured_LED_init
bl red_led_on
#endif
/* call board_init_r(gd_t *id, ulong dest_addr) */
mov r0, r9 /* gd_t */
ldr r1, [r9, #GD_RELOCADDR] /* dest_addr */
/* call board_init_r */
ldr pc, =board_init_r /* this is auto-relocated! */
/* we should not return here. */
#endif
ENDPROC(_main)然后调用了 board_init_r 函数
common\board_r.c
void board_init_r(gd_t *new_gd, ulong dest_addr)
{
#ifdef CONFIG_NEEDS_MANUAL_RELOC
int i;
#endif
#ifdef CONFIG_AVR32
mmu_init_r(dest_addr);
#endif
#if !defined(CONFIG_X86) && !defined(CONFIG_ARM) && !defined(CONFIG_ARM64)
gd = new_gd;
#endif
#ifdef CONFIG_NEEDS_MANUAL_RELOC
for (i = 0; i < ARRAY_SIZE(init_sequence_r); i++)
init_sequence_r[i] += gd->reloc_off;
#endif
if (initcall_run_list(init_sequence_r)) //只是一个函数指针的数组，里面包含了一系列初始化函数
hang();
/* NOTREACHED - run_main_loop() does not return */
hang();
}我们来看看这个init_sequence_r 为了更加清晰的看到他的流程，我删减了一部分代码
init_fnc_t init_sequence_r[] = {
initr_trace,
initr_reloc,
/* TODO: could x86/PPC have this also perhaps? */
#ifdef CONFIG_ARM
initr_caches,
#endif
initr_reloc_global_data,
。。。。。。。
board_init, /* Setup chipselects */
#endif
/*
* TODO: printing of the clock inforamtion of the board is now
* implemented as part of bdinfo command. Currently only support for
* davinci SOC's is added. Remove this check once all the board
* implement this.
*/
。。。。。。。。
INIT_FUNC_WATCHDOG_RESET
#ifdef CONFIG_SYS_DELAYED_ICACHE
initr_icache_enable,
#endif
#if defined(CONFIG_PCI) && defined(CONFIG_SYS_EARLY_PCI_INIT)
/*
* Do early PCI configuration _before_ the flash gets initialised,
* because PCU ressources are crucial for flash access on some boards.
*/
initr_pci,
#endif
。。。。。。。
#ifdef CONFIG_ARCH_MISC_INIT
arch_misc_init, /* miscellaneous arch-dependent init */
#endif
#ifdef CONFIG_MISC_INIT_R
misc_init_r, /* miscellaneous platform-dependent init */
#endif
INIT_FUNC_WATCHDOG_RESET
。。。。。。。
#if defined(CONFIG_X86) || defined(CONFIG_MICROBLAZE) || defined(CONFIG_AVR32) \
|| defined(CONFIG_M68K)
timer_init, /* initialize timer */
#endif
INIT_FUNC_WATCHDOG_RESET
/*
* Some parts can be only initialized if all others (like
* Interrupts) are up and running (i.e. the PC-style ISA
* keyboard).
*/
last_stage_init,
#endif
#ifdef CONFIG_CMD_BEDBUG
INIT_FUNC_WATCHDOG_RESET
initr_bedbug,
#endif
#if defined(CONFIG_PRAM) || defined(CONFIG_LOGBUFFER)
initr_mem,
#endif
#ifdef CONFIG_PS2KBD
initr_kbd,
#endif
#ifdef CONFIG_FSL_FASTBOOT
initr_check_fastboot,
#endif
run_main_loop,
};
这里满足宏条件的函数都会被执行，最后一个执行的函数是run_main_loop，我继续追踪下去，这个函数 还是在这个文件中board_r.c
static int run_main_loop(void)
{
#ifdef CONFIG_SANDBOX
sandbox_main_loop_init();
#endif
/* main_loop() can return to retry autoboot, if so just run it again */
for (;;) //死循环
main_loop();
return 0;
}可以看见，这里是单向的，调用了run_main_loop就不会返回了，我们继续看看main_loop();
common\main.c
/* We come here after U-Boot is initialised and ready to process commands */
void main_loop(void)
{
const char *s;
。。。。。。。。。
puts("#test!!!!!!!!!!!!!!!!!!!!!!!\n");
modem_init();
#ifdef CONFIG_VERSION_VARIABLE
setenv("ver", version_string); /* set version variable */
#endif /* CONFIG_VERSION_VARIABLE */
cli_init();
run_preboot_environment_command();
#if defined(CONFIG_UPDATE_TFTP)
update_tftp(0UL);
#endif /* CONFIG_UPDATE_TFTP */
s = bootdelay_process(); //uboot读秒，等待用户按键
if (cli_process_fdt(&s))
cli_secure_boot_cmd(s);
printf("flag2");
autoboot_command(s); //用户没有按键，执行环境参数命令
cli_loop();
}我们 继续进入到 autoboot_command(s);
void autoboot_command(const char *s)
{
debug("### main_loop: bootcmd=\"%s\"\n", s ? s : "<UNDEFINED>");
if (stored_bootdelay != -1 && s && !abortboot(stored_bootdelay)) {
#if defined(CONFIG_AUTOBOOT_KEYED) && !defined(CONFIG_AUTOBOOT_KEYED_CTRLC)
int prev = disable_ctrlc(1); /* disable Control C checking */
#endif
run_command_list(s, -1, 0); //传递过来的命令流s会在这里被解析执行
#if defined(CONFIG_AUTOBOOT_KEYED) && !defined(CONFIG_AUTOBOOT_KEYED_CTRLC)
disable_ctrlc(prev); /* restore Control C checking */
#endif
}
#ifdef CONFIG_MENUKEY
if (menukey == CONFIG_MENUKEY) {
s = getenv("menucmd");
if (s)
run_command_list(s, -1, 0);
}
#endif /* CONFIG_MENUKEY */
}对于命令的解析执行，我们追踪 run_command_list(s, -1, 0);来分析分析
int run_command_list(const char *cmd, int len, int flag)
{
int need_buff = 1;
char *buff = (char *)cmd; /* cast away const */
int rcode = 0;
if (len == -1) {
len = strlen(cmd);
#ifdef CONFIG_SYS_HUSH_PARSER
/* hush will never change our string */
need_buff = 0;
#else
/* the built-in parser will change our string if it sees \n */
need_buff = strchr(cmd, '\n') != NULL;
#endif
}
if (need_buff) {
buff = malloc(len + 1);
if (!buff)
return 1;
memcpy(buff, cmd, len);
buff[len] = '\0';
}
#ifdef CONFIG_SYS_HUSH_PARSER
rcode = parse_string_outer(buff, FLAG_PARSE_SEMICOLON);
#else
。。。。。。。。。
#endif
return rcode;
}继续追踪parse_string_outer(buff, FLAG_PARSE_SEMICOLON);
#ifndef __U_BOOT__
static int parse_string_outer(const char *s, int flag)
#else
int parse_string_outer(const char *s, int flag)
#endif /* __U_BOOT__ */
{
struct in_str input;
#ifdef __U_BOOT__
char *p = NULL;
int rcode;
if (!s)
return 1;
if (!*s)
return 0;
if (!(p = strchr(s, '\n')) || *++p) {
p = xmalloc(strlen(s) + 2);
strcpy(p, s);
strcat(p, "\n");
setup_string_in_str(&input, p);
rcode = parse_stream_outer(&input, flag);
free(p);
return rcode;
} else {
#endif
setup_string_in_str(&input, s);
return parse_stream_outer(&input, flag);
#ifdef __U_BOOT__
}
#endif
}这里主要是对命令流进行了分割、执行。我们再继续追踪 parse_stream_outer(&input, flag);
/* most recursion does not come through here, the exeception is
* from builtin_source() */
static int parse_stream_outer(struct in_str *inp, int flag)
{
struct p_context ctx;
o_string temp=NULL_O_STRING;
int rcode;
#ifdef __U_BOOT__
int code = 1;
#endif
do {
ctx.type = flag;
initialize_context(&ctx);
update_ifs_map();
if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING)) mapset((uchar *)";$&|", 0);
inp->promptmode=1;
rcode = parse_stream(&temp, &ctx, inp,
flag & FLAG_CONT_ON_NEWLINE ? -1 : '\n');
#ifdef __U_BOOT__
if (rcode == 1) flag_repeat = 0;
#endif
if (rcode != 1 && ctx.old_flag != 0) {
syntax();
#ifdef __U_BOOT__
flag_repeat = 0;
#endif
}
if (rcode != 1 && ctx.old_flag == 0) {
done_word(&temp, &ctx);
done_pipe(&ctx,PIPE_SEQ);
#ifndef __U_BOOT__
run_list(ctx.list_head); //执行命令
#else
。。。。。。。。
#endif
} else {
if (ctx.old_flag != 0) {
free(ctx.stack);
b_reset(&temp);
}
#ifdef __U_BOOT__
if (inp->__promptme == 0) printf("<INTERRUPT>\n");
inp->__promptme = 1;
#endif
temp.nonnull = 0;
temp.quote = 0;
inp->p = NULL;
free_pipe_list(ctx.list_head,0);
}
b_free(&temp);
/* loop on syntax errors, return on EOF */
} while (rcode != -1 && !(flag & FLAG_EXIT_FROM_LOOP) &&
(inp->peek != static_peek || b_peek(inp)));
#ifndef __U_BOOT__
return 0;
#else
return (code != 0) ? 1 : 0;
#endif /* __U_BOOT__ */
}追踪run_list(ctx.list_head);
/* Select which version we will use */
static int run_list(struct pipe *pi)
{
int rcode=0;
#ifndef __U_BOOT__
if (fake_mode==0) {
#endif
rcode = run_list_real(pi);
#ifndef __U_BOOT__
}
#endif
/* free_pipe_list has the side effect of clearing memory
* In the long run that function can be merged with run_list_real,
* but doing that now would hobble the debugging effort. */
free_pipe_list(pi,0);
return rcode;
}追踪 run_list_real(pi);
static int run_list_real(struct pipe *pi)
{
char *save_name = NULL;
char **list = NULL;
char **save_list = NULL;
struct pipe *rpipe;
int flag_rep = 0;
#ifndef __U_BOOT__
int save_num_progs;
#endif
int rcode=0, flag_skip=1;
int flag_restore = 0;
int if_code=0, next_if_code=0; /* need double-buffer to handle elif */
reserved_style rmode, skip_more_in_this_rmode=RES_XXXX;
/* check syntax for "for" */
for (rpipe = pi; rpipe; rpipe = rpipe->next) {
if ((rpipe->r_mode == RES_IN ||
rpipe->r_mode == RES_FOR) &&
(rpipe->next == NULL)) {
syntax();
#ifdef __U_BOOT__
flag_repeat = 0;
#endif
return 1;
}
if ((rpipe->r_mode == RES_IN &&
(rpipe->next->r_mode == RES_IN &&
rpipe->next->progs->argv != NULL))||
(rpipe->r_mode == RES_FOR &&
rpipe->next->r_mode != RES_IN)) {
syntax();
#ifdef __U_BOOT__
flag_repeat = 0;
#endif
return 1;
}
}
for (; pi; pi = (flag_restore != 0) ? rpipe : pi->next) {
if (pi->r_mode == RES_WHILE || pi->r_mode == RES_UNTIL ||
pi->r_mode == RES_FOR) {
#ifdef __U_BOOT__
。。。。。。。。。。
#endif
。。。。。。。。。。
#ifndef __U_BOOT__
pi->progs->glob_result.gl_pathv[0] =
pi->progs->argv[0];
#endif
continue;
} else {
/* insert new value from list for variable */
if (pi->progs->argv[0])
free(pi->progs->argv[0]);
pi->progs->argv[0] = *list++;
#ifndef __U_BOOT__
pi->progs->glob_result.gl_pathv[0] =
pi->progs->argv[0];
#endif
}
}
if (rmode == RES_IN) continue;
if (rmode == RES_DO) {
if (!flag_rep) continue;
}
if (rmode == RES_DONE) {
if (flag_rep) {
flag_restore = 1;
} else {
rpipe = NULL;
}
}
if (pi->num_progs == 0) continue;
#ifndef __U_BOOT__
save_num_progs = pi->num_progs; /* save number of programs */
#endif
rcode = run_pipe_real(pi); //执行
debug_printf("run_pipe_real returned %d\n",rcode);
#ifndef __U_BOOT__
if (rcode!=-1) {
/* We only ran a builtin: rcode was set by the return value
* of run_pipe_real(), and we don't need to wait for anything. */
} else if (pi->followup==PIPE_BG) {
/* XXX check bash's behavior with nontrivial pipes */
/* XXX compute jobid */
/* XXX what does bash do with attempts to background builtins? */
insert_bg_job(pi);
rcode = EXIT_SUCCESS;
} else {
。。。。。。。
} else {
rcode = checkjobs(pi);
}
debug_printf("checkjobs returned %d\n",rcode);
}
last_return_code=rcode;
#else
if (rcode < -1) {
last_return_code = -rcode - 2;
return -2; /* exit */
}
last_return_code=(rcode == 0) ? 0 : 1;
#endif
#ifndef __U_BOOT__
pi->num_progs = save_num_progs; /* restore number of programs */
#endif
if ( rmode == RES_IF || rmode == RES_ELIF )
next_if_code=rcode; /* can be overwritten a number of times */
if (rmode == RES_WHILE)
flag_rep = !last_return_code;
if (rmode == RES_UNTIL)
flag_rep = last_return_code;
if ( (rcode==EXIT_SUCCESS && pi->followup==PIPE_OR) ||
(rcode!=EXIT_SUCCESS && pi->followup==PIPE_AND) )
skip_more_in_this_rmode=rmode;
#ifndef __U_BOOT__
checkjobs(NULL);
#endif
}
return rcode;
}追踪 rcode = run_pipe_real(pi);
/* run_pipe_real() starts all the jobs, but doesn't wait for anything
* to finish. See checkjobs().
*
* return code is normally -1, when the caller has to wait for children
* to finish to determine the exit status of the pipe. If the pipe
* is a simple builtin command, however, the action is done by the
* time run_pipe_real returns, and the exit code is provided as the
* return value.
*
* The input of the pipe is always stdin, the output is always
* stdout. The outpipe[] mechanism in BusyBox-0.48 lash is bogus,
* because it tries to avoid running the command substitution in
* subshell, when that is in fact necessary. The subshell process
* now has its stdout directed to the input of the appropriate pipe,
* so this routine is noticeably simpler.
*/
static int run_pipe_real(struct pipe *pi)
{
int i;
#ifndef __U_BOOT__
int nextin, nextout;
int pipefds[2]; /* pipefds[0] is for reading */
struct child_prog *child;
struct built_in_command *x;
char *p;
# if __GNUC__
/* Avoid longjmp clobbering */
(void) &i;
(void) &nextin;
(void) &nextout;
(void) &child;
# endif
#else
int nextin;
int flag = do_repeat ? CMD_FLAG_REPEAT : 0;
struct child_prog *child;
char *p;
# if __GNUC__
/* Avoid longjmp clobbering */
(void) &i;
(void) &nextin;
(void) &child;
# endif
#endif /* __U_BOOT__ */
nextin = 0;
#ifndef __U_BOOT__
pi->pgrp = -1;
#endif
/* Check if this is a simple builtin (not part of a pipe).
* Builtins within pipes have to fork anyway, and are handled in
* pseudo_exec. "echo foo | read bar" doesn't work on bash, either.
*/
if (pi->num_progs == 1) child = & (pi->progs[0]);
#ifndef __U_BOOT__
。。。。。。。
#else
if (pi->num_progs == 1 && child->group) {
int rcode;
debug_printf("non-subshell grouping\n");
rcode = run_list_real(child->group);
#endif
return rcode;
} else if (pi->num_progs == 1 && pi->progs[0].argv != NULL) {
for (i=0; is_assignment(child->argv[i]); i++) { /* nothing */ }
if (i!=0 && child->argv[i]==NULL) {
/* assignments, but no command: set the local environment */
for (i=0; child->argv[i]!=NULL; i++) {
/* Ok, this case is tricky. We have to decide if this is a
* local variable, or an already exported variable. If it is
* already exported, we have to export the new value. If it is
* not exported, we need only set this as a local variable.
* This junk is all to decide whether or not to export this
* variable. */
int export_me=0;
char *name, *value;
name = xstrdup(child->argv[i]);
debug_printf("Local environment set: %s\n", name);
value = strchr(name, '=');
if (value)
*value=0;
#ifndef __U_BOOT__
if ( get_local_var(name)) {
export_me=1;
}
#endif
free(name);
p = insert_var_value(child->argv[i]);
set_local_var(p, export_me);
if (p != child->argv[i]) free(p);
}
return EXIT_SUCCESS; /* don't worry about errors in set_local_var() yet */
}
for (i = 0; is_assignment(child->argv[i]); i++) {
p = insert_var_value(child->argv[i]);
#ifndef __U_BOOT__
putenv(strdup(p));
#else
set_local_var(p, 0);
#endif
if (p != child->argv[i]) {
child->sp--;
free(p);
}
}
if (child->sp) {
char * str = NULL;
str = make_string(child->argv + i,
child->argv_nonnull + i);
parse_string_outer(str, FLAG_EXIT_FROM_LOOP | FLAG_REPARSING);
free(str);
return last_return_code;
}
#ifndef __U_BOOT__
。。。。。。。。
#else
/* check ";", because ,example , argv consist from
* "help;flinfo" must not execute
*/
if (strchr(child->argv[i], ';')) {
printf("Unknown command '%s' - try 'help' or use "
"'run' command\n", child->argv[i]);
return -1;
}
/* Process the command */
return cmd_process(flag, child->argc, child->argv,
&flag_repeat, NULL);
#endif
}追踪 cmd_process(flag, child->argc, child->argv, &flag_repeat, NULL);
enum command_ret_t cmd_process(int flag, int argc, char * const argv[],
int *repeatable, ulong *ticks)
{
enum command_ret_t rc = CMD_RET_SUCCESS;
cmd_tbl_t *cmdtp;
/* Look up command in command table */
cmdtp = find_cmd(argv[0]);
if (cmdtp == NULL) {
printf("Unknown command '%s' - try 'help'\n", argv[0]);
return 1;
}
/* found - check max args */
if (argc > cmdtp->maxargs)
rc = CMD_RET_USAGE;
#if defined(CONFIG_CMD_BOOTD)
/* avoid "bootd" recursion */
else if (cmdtp->cmd == do_bootd) {
if (flag & CMD_FLAG_BOOTD) {
puts("'bootd' recursion detected\n");
rc = CMD_RET_FAILURE;
} else {
flag |= CMD_FLAG_BOOTD;
}
}
#endif
/* If OK so far, then do the command */
if (!rc) {
if (ticks)
*ticks = get_timer(0);
rc = cmd_call(cmdtp, flag, argc, argv);
if (ticks)
*ticks = get_timer(*ticks);
*repeatable &= cmdtp->repeatable;
}
if (rc == CMD_RET_USAGE)
rc = cmd_usage(cmdtp);
return rc;
}命令最终在这里被执行，以上一系列过程 将收到的指令通过一系列字符处理然后加入一个执行列表，然后执行这个列表。这些命令的的具体实现大家可以 执行 find -name ./common/cmd*.c
这些文件里定义了命令的具体实现。
比如我们mmc read xx xx命令，在common\cmd_mmc.c :842中，大家可以具体去看看,其实读秒过后的，系统自动执行了一系列环境变量（）中保存的命令，执行命令这一套的通用的，只是命令的来源不一样，一个是用户输入的，一个是从环境命令中读取的。我们可以做个实验，在parse_string_outer函数中添加如下代码
#ifndef __U_BOOT__
static int parse_string_outer(const char *s, int flag)
#else
int parse_string_outer(const char *s, int flag)
#endif /* __U_BOOT__ */
{
struct in_str input;
#ifdef __U_BOOT__
char *p = NULL;
int rcode;
if (!s)
return 1;
if (!*s)
return 0;
if (!(p = strchr(s, '\n')) || *++p) {
p = xmalloc(strlen(s) + 2)
printf("#stream =%s \n", s); //yin
strcpy(p, s);
strcat(p, "\n");
printf("#hush\n"); //yin
setup_string_in_str(&input, p);
rcode = parse_stream_outer(&input, flag);
free(p);
return rcode;
} else {
#endif
setup_string_in_str(&input, s);
return parse_stream_outer(&input, flag);
#ifdef __U_BOOT__
}
#endif
}然后编译，烧写，启动，观察输出信息
U-Boot 2015.04 (Mar 16 2018 - 18:45:12)
CPU: Freescale i.MX6Q rev1.5 at 792 MHz
CPU: Temperature 35 C
Reset cause: POR
Board: MYZR i.MX6 Evaluation Kit
Model: MY-IMX6-EK314-6Q-1G
I2C: ready
DRAM: 1 GiB
MMC: FSL_SDHC: 0, FSL_SDHC: 1
SF: Detected SST25VF016B with page size 256 Bytes, erase size 4 KiB, total 2 MiB
*** Warning - bad CRC, using default environment
No panel detected: default to Hannstar-XGA
Display: Hannstar-XGA (1024x600)
In: serial
Out: serial
Err: serial
Net: using phy at 5
FEC [PRIME]
#test!!!!!!!!!!!!!!!!!!!!
Normal Boot
flag1
flag2Hit any key to stop autoboot: 0
#run start
stream = mmc dev ${mmcdev}; if run loadimage; then run mmcboot; else run netboot; fi;
#hush
switch to partitions #0, OK
mmc1(part 0) is current device
stream = fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${image_file}
#hush
reading zImage-myimx6
5602432 bytes read in 157 ms (34 MiB/s)
stream = echo Booting from mmc ...; run mmcargs; if run loadfdt; then bootz ${loadaddr} - ${fdt_addr}; else echo WARN: Cannot boot from mmc; fi;
#hush
Booting from mmc ...
stream = run set_disp; setenv bootargs console=${console},${baudrate} ${smp} cma=320M root=${mmcroot} ${disp_args}
#hush
stream = setenv disp_args ${display}
#hush
stream = fatload mmc ${mmcdev}:${mmcpart} ${fdt_addr} ${fdt_file}
#hush
reading myimx6ek314-6q.dtb
42887 bytes read in 18 ms (2.3 MiB/s)
Kernel image @ 0x12000000 [ 0x000000 - 0x557c80 ]
## Flattened Device Tree blob at 18000000
Booting using the fdt blob at 0x18000000
Using Device Tree in place at 18000000, end 1800d786
Starting kernel ...分析到这里想必大家都有了自己想法，剩下的就交给你们去探索了，这里仅仅是个抛砖引玉，做个粗浅的分析，感谢您耐着性子读到这里，哈哈哈~~
lornyin 2018/3/17