bootz启动 Linux内核过程中涉及的 do_bootm_states 函数

一.  bootz启动Linux

uboot 启动Linux内核使用bootz命令。当然还有其它的启动命令，例如，bootm命令等等。

本文只分析 bootz命令启动 Linux内核的过程中涉及的几个重要函数。具体分析  do_bootm_states 函数执行过程。

本文继上一篇文章，地址如下：

bootz启动 Linux内核过程中涉及的 bootz_start 函数-CSDN博客

二.  bootz 启动 Linux 内核涉及函数

bootz 命令的执行函数为 do_bootz函数。而 do_bootz函数主要调用如下函数：

bootz_start 函数，bootm_disable_interrupts 函数，设置 images.os.os ，do_bootm_states 函数。

1.  do_bootm_states 函数

BOOTM_STATE_OS_PREP
BOOTM_STATE_OS_FAKE_GO
BOOTM_STATE_OS_GO
BOOTM_STATE_START

int do_bootm_states(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
		    int states, bootm_headers_t *images, int boot_progress)
{
	boot_os_fn *boot_fn;
	ulong iflag = 0;
	int ret = 0, need_boot_fn;
 
	images->state |= states;
............
	/* From now on, we need the OS boot function */
	if (ret)
		return ret;
	boot_fn = bootm_os_get_boot_func(images->os.os);
	need_boot_fn = states & (BOOTM_STATE_OS_CMDLINE |
			BOOTM_STATE_OS_BD_T | BOOTM_STATE_OS_PREP |
			BOOTM_STATE_OS_FAKE_GO | BOOTM_STATE_OS_GO);
	if (boot_fn == NULL && need_boot_fn) {
		if (iflag)
			enable_interrupts();
		printf("ERROR: booting os '%s' (%d) is not supported\n",
		       genimg_get_os_name(images->os.os), images->os.os);
		bootstage_error(BOOTSTAGE_ID_CHECK_BOOT_OS);
		return 1;
	}
............
	if (!ret && (states & BOOTM_STATE_OS_PREP))
		ret = boot_fn(BOOTM_STATE_OS_PREP, argc, argv, images);
 
#ifdef CONFIG_TRACE
	/* Pretend to run the OS, then run a user command */
	if (!ret && (states & BOOTM_STATE_OS_FAKE_GO)) {
		char *cmd_list = getenv("fakegocmd");
 
		ret = boot_selected_os(argc, argv, BOOTM_STATE_OS_FAKE_GO,
				images, boot_fn);
		if (!ret && cmd_list)
			ret = run_command_list(cmd_list, -1, flag);
	}
#endif
 
	/* Check for unsupported subcommand. */
	if (ret) {
		puts("subcommand not supported\n");
		return ret;
	}
 
	/* Now run the OS! We hope this do not return */
	if (!ret && (states & BOOTM_STATE_OS_GO))
		ret = boot_selected_os(argc, argv, BOOTM_STATE_OS_GO,
				images, boot_fn);
 
.............
	return ret;
}

int boot_selected_os(int argc, char * const argv[], int state, bootm_headers_t *images, boot_os_fn *boot_fn)
{
	arch_preboot_os();
	boot_fn(state, argc, argv, images);
 
	/* Stand-alone may return when 'autostart' is 'no' */
	if (images->os.type == IH_TYPE_STANDALONE ||
	    state == BOOTM_STATE_OS_FAKE_GO) /* We expect to return */
		return 0;
	bootstage_error(BOOTSTAGE_ID_BOOT_OS_RETURNED);
#ifdef DEBUG
	puts("\n## Control returned to monitor - resetting...\n");
#endif
	return BOOTM_ERR_RESET;
}

do_bootm_linux 函数简化代码如下，这里只列出此处会执行到代码：

int do_bootm_states(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
		    int states, bootm_headers_t *images, int boot_progress)
{
	boot_os_fn *boot_fn;
	ulong iflag = 0;
	int ret = 0, need_boot_fn;
 
	images->state |= states;
.............
 
	if (!ret && (states & BOOTM_STATE_OS_GO))
		ret = boot_selected_os(argc, argv, BOOTM_STATE_OS_GO,
				images, boot_fn);
.............
	return ret;
}