方法一:
common/main.c
void main_loop(void)
{
const char *s;
bootstage_mark_name(BOOTSTAGE_ID_MAIN_LOOP, "main_loop");
if (IS_ENABLED(CONFIG_VERSION_VARIABLE))
env_set("ver", version_string); /* set version variable */
cli_init();
s = env_get("bootcmd");
printf(" cli_init env_get bootcmd is %s run_command_list\r\n",s);
run_command_list(s, -1, 0); // 启动内核
if (IS_ENABLED(CONFIG_USE_PREBOOT))
run_preboot_environment_command();
if (IS_ENABLED(CONFIG_UPDATE_TFTP))
update_tftp(0UL, NULL, NULL);
s = bootdelay_process();
if (cli_process_fdt(&s))
cli_secure_boot_cmd(s);
autoboot_command(s);
cli_loop();
panic("No CLI available");
}
方法二:
common/autoboot.c
void autoboot_command(const char *s)
{
debug("### main_loop: bootcmd=\"%s\"\n", s ? s : "<UNDEFINED>");
if (stored_bootdelay != -1 && s && !abortboot(stored_bootdelay)) {
bool lock;
int prev;
lock = IS_ENABLED(CONFIG_AUTOBOOT_KEYED) &&
!IS_ENABLED(CONFIG_AUTOBOOT_KEYED_CTRLC);
if (lock)
prev = disable_ctrlc(1); /* disable Ctrl-C checking */
run_command_list(s, -1, 0);
if (lock)
disable_ctrlc(prev); /* restore Ctrl-C checking */
}
if (IS_ENABLED(CONFIG_USE_AUTOBOOT_MENUKEY) &&
menukey == AUTOBOOT_MENUKEY) {
s = env_get("menucmd");
if (s)
run_command_list(s, -1, 0);
}
}
static int abortboot(int bootdelay)
{
int abort = 0;
return 0 ; // 直接返回
if (bootdelay >= 0) {
if (IS_ENABLED(CONFIG_AUTOBOOT_KEYED))
abort = abortboot_key_sequence(bootdelay);
else
abort = abortboot_single_key(bootdelay);
}
if (IS_ENABLED(CONFIG_SILENT_CONSOLE) && abort)
gd->flags &= ~GD_FLG_SILENT;
return abort;
}
void autoboot_command(const char *s)
{
debug("### main_loop: bootcmd=\"%s\"\n", s ? s : "<UNDEFINED>");
if (stored_bootdelay != -1 && s && !abortboot(stored_bootdelay)) {
bool lock;
int prev;
lock = IS_ENABLED(CONFIG_AUTOBOOT_KEYED) &&
!IS_ENABLED(CONFIG_AUTOBOOT_KEYED_CTRLC);
if (lock)
prev = disable_ctrlc(1); /* disable Ctrl-C checking */
run_command_list(s, -1, 0); // 启动内核
if (lock)
disable_ctrlc(prev); /* restore Ctrl-C checking */
}
if (IS_ENABLED(CONFIG_USE_AUTOBOOT_MENUKEY) &&
menukey == AUTOBOOT_MENUKEY) {
s = env_get("menucmd");
if (s)
run_command_list(s, -1, 0);
}
}
static int abortboot_single_key(int bootdelay)
{
int abort = 0;
unsigned long ts;
printf("Hit any key to stop autoboot: %2d ", bootdelay); // 打印
/*
* Check if key already pressed
*/
if (tstc()) { /* we got a key press */
(void) getc(); /* consume input */
puts("\b\b\b 0");
abort = 1; /* don't auto boot */
}
while ((bootdelay > 0) && (!abort)) {
--bootdelay;
/* delay 1000 ms */
ts = get_timer(0);
do {
if (tstc()) { /* we got a key press */
int key;
abort = 1; /* don't auto boot */
bootdelay = 0; /* no more delay */
key = getc(); /* consume input */
if (IS_ENABLED(CONFIG_USE_AUTOBOOT_MENUKEY))
menukey = key;
break;
}
udelay(10000);
} while (!abort && get_timer(ts) < 1000);
printf("\b\b\b%2d ", bootdelay); // 打印倒计时
}
putc('\n');
return abort;
}