如在uEnv.txt中，
loadfdt=fatload mmc ${mmcdev}:1 ${fdtaddr} ${fdtfile}
fdtboot=run mmc_args; bootz ${loadaddr} - ${fdtaddr}
uenvcmd=mmc rescan; run loaduimage; run loadfdt; run fdtboot
uboot中：
include/configs/am43xx_evm.h
#define CONFIG_EXTRA_ENV_SETTINGS DEFAULT_LINUX_BOOT_ENV DEFAULT_MMC_TI_ARGS
......