setup_machine_fdt
extern const struct machine_desc *setup_machine_fdt(void *dt);
machine_desc = setup_machine_fdt((void *)uboot_arg);
machine_desc = setup_machine_fdt(__dtb_start);
extern const struct machine_desc *setup_machine_fdt(void *dt_virt);
mdesc = setup_machine_fdt(atags_vaddr);
setup_machine_fdt(__fdt_pointer);