看下面的例子就清楚了。
static int __def_eth_init(bd_t *bis)
{
return -1;
}
int board_eth_init(bd_t *bis) __attribute__((weak, alias("__def_eth_init")));
/*
* If board-specific initialization exists, call it.
* If not, call a CPU-specific one
*/
if (board_eth_init != __def_eth_init) {
if (board_eth_init(gd->bd) < 0)
printf("Board Net Initialization Failed\n");