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int do_bootm (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
{
ulong iflag;
ulong load_end = 0;
int ret;
boot_os_fn *boot_fn;
#ifndef CONFIG_RELOC_FIXUP_WORKS
static int relocated = 0;
/* relocate boot function table */
if (!relocated) {
int i;
for (i = 0; i < ARRAY_SIZE(boot_os); i++)
if (boot_os[i] != NULL)
boot_os[i] += gd->reloc_off;
relocated = 1;
}
#endif
/* determine if we have a sub command */
if (argc > 1) {
char *endp;
simple_strtoul(argv[1], &endp, 16);
if ((*endp != 0) && (*endp != ':') && (*endp != '#'))
return do_bootm_subcommand(cmdtp, flag, argc, argv);
}
if (bootm_start(cmdtp, flag, argc, argv)) //提取mkimage生成的文件头部，放到bootm_headers_t结构体中
return 1;
iflag = disable_interrupts();
#if defined(CONFIG_CMD_USB)
usb_stop();
#endif
#ifdef CONFIG_AMIGAONEG3SE
/*
* We've possible left the caches enabled during
* bios emulation, so turn them off again
*/
icache_disable();
dcache_disable();
#endif
ret = bootm_load_os(images.os, &load_end, 1); //加载操作系统的关键部分 确定使用的地址
if (ret < 0) { //出错处理
if (ret == BOOTM_ERR_RESET)
do_reset (cmdtp, flag, argc, argv);
if (ret == BOOTM_ERR_OVERLAP) {
if (images.legacy_hdr_valid) {
if (image_get_type (&images.legacy_hdr_os_copy) == IH_TYPE_MULTI)
puts ("WARNING: legacy format multi component "
"image overwritten\n");
} else {
puts ("ERROR: new format image overwritten - "
"must RESET the board to recover\n");
show_boot_progress (-113);
do_reset (cmdtp, flag, argc, argv);
}
}
if (ret == BOOTM_ERR_UNIMPLEMENTED) {
if (iflag)
enable_interrupts();
show_boot_progress (-7);
return 1;
}
}
lmb_reserve(&images.lmb, images.os.load, (load_end - images.os.load));
if (images.os.type == IH_TYPE_STANDALONE) {//独立的应用程序
if (iflag)
enable_interrupts();
/* This may return when 'autostart' is 'no' */
bootm_start_standalone(iflag, argc, argv);
return 0;
}
show_boot_progress (8);
#ifdef CONFIG_SILENT_CONSOLE //这里处理Linux操作系统
if (images.os.os == IH_OS_LINUX)
fixup_silent_linux(); //该函数中处理bootarg参数
#endif
boot_fn = boot_os[images.os.os];
if (boot_fn == NULL) {
if (iflag)
enable_interrupts();
printf ("ERROR: booting os '%s' (%d) is not supported\n",
genimg_get_os_name(images.os.os), images.os.os);
show_boot_progress (-8);
return 1;
}
arch_preboot_os();
/*下面的函数，继续引导内核的镜像，复制image header 到全局变量header；
检查header的魔数，检查数，header和image中的这两个。确定image的体系结构和类型（KERNEL or MULTI）,关闭中断，加载image到header中的加载地址*/
boot_fn(0, argc, argv, &images); //调用do_bootm_linux()函数
show_boot_progress (-9);
#ifdef DEBUG
puts ("\n## Control returned to monitor - resetting...\n");
#endif
do_reset (cmdtp, flag, argc, argv);
return 1;
}
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