uboot源码阅读（八）江湖人物go

 我们把去掉符号链接等的bin文件,加载到内存中以后使用命令go就可以执行这个程序.

我感觉还是比较好理解的，不知道还是我没理解好！

int do_go (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
{
	ulong	addr, rc;
	int     rcode = 0;

	if (argc < 2) {
		printf ("Usage:\n%s\n", cmdtp->usage);
		return 1;
	}

	addr = simple_strtoul(argv[1], NULL, 16);

	printf ("## Starting application at 0x%08lX ...\n", addr);

	/*
	 * pass address parameter as argv[0] (aka command name),
	 * and all remaining args
	 */
#if defined(CONFIG_I386)
	/*
	 * x86 does not use a dedicated register to pass the pointer
	 * to the global_data
	 */
	argv[0] = (char *)gd;
#endif
#if !defined(CONFIG_NIOS)
	rc = ((ulong (*)(int, char *[]))addr) (--argc, &argv[1]);//这里是把要执行的位置的地址强制转化为函数指针，类似程序的入口地址
#else
	/*
	 * Nios function pointers are address >> 1
	 */
	rc = ((ulong (*)(int, char *[]))(addr>>1)) (--argc, &argv[1]);
#endif
	if (rc != 0) rcode = 1;

	printf ("## Application terminated, rc = 0x%lX\n", rc);
	return rcode;
}

/* -------------------------------------------------------------------- */
//向命令列表里面注册go命令
U_BOOT_CMD(
	go, CFG_MAXARGS, 1,	do_go,
	"go      - start application at address 'addr'\n",
	"addr [arg ...]\n    - start application at address 'addr'\n"
	"      passing 'arg' as arguments\n"
);

转载请注明出处: http://blog.csdn.net/ecbtnrt/article/details/6635792