setenv update_uboot  'fatload mmc ${drive}:1 ${loadaddr} u-boot.imx && setexpr blkcnt $filesize + 0x1ff && setexpr blkcnt ${blkcnt} / 0x200 && mmc dev 0 && mmc write ${loadaddr} 2 ${blkcnt}'
echo 'enter "run update_uboot" to update the uboot'