uboot源码阅读（八）江湖人物go

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"
);