int fdtdec_setup(void)

 

/lib/fdtdec.c

int fdtdec_setup(void)
{
#if CONFIG_IS_ENABLED(OF_CONTROL)
# ifdef CONFIG_OF_EMBED
    /* Get a pointer to the FDT */
    gd->fdt_blob = __dtb_dt_begin;
# elif defined CONFIG_OF_SEPARATE
#  ifdef CONFIG_SPL_BUILD
    /* FDT is at end of BSS unless it is in a different memory region */
    if (IS_ENABLED(CONFIG_SPL_SEPARATE_BSS))
        gd->fdt_blob = (ulong *)&_image_binary_end;
    else
        gd->fdt_blob = (ulong *)&__bss_end;
#  else
    /* FDT is at end of image */
    gd->fdt_blob = (ulong *)&_end;
#  endif
# elif defined(CONFIG_OF_HOSTFILE)
    if (sandbox_read_fdt_from_file()) {
        puts("Failed to read control FDT\n");
        return -1;
    }
# endif
# ifndef CONFIG_SPL_BUILD
    /* Allow the early environment to override the fdt address */
    gd->fdt_blob = (void *)getenv_ulong("fdtcontroladdr", 16,
                        (uintptr_t)gd->fdt_blob);
# endif
#endif
    return fdtdec_prepare_fdt();
}

 

16번 라인이 실행

근데 _image_binary_end랑 _end랑 같다.

24번 라인 CONFIG_SPL_BUILD가 정의되어있지 않기때문에 26번라인 실행

 

fdt_blob은 디바이스트리의 위치를 나타내는것 같다.

26번라인 getenv_ulong은 fdtcontroladdr의 환경변수 값을 얻어올수 있다.

더적확히는 getenv함수에서 fdtcontroladdr의 환경변수값을 읽어올수 있고,