mmc dev 0
mmc rescan
mmc dev 1

fatload mmc 0 ${loadaddr} MLO
mmc write ${loadaddr} 0x100 0x100
mmc write ${loadaddr} 0x200 0x100

fatload mmc 0 ${loadaddr} u-boot.img
mmc write ${loadaddr} 0x300 0x4000x1300

dd if=/run/media/mmcblk0p1/MLO of=/dev/mmcblk1 seek=256 count=256
dd if=/run/media/mmcblk0p1/MLO of=/dev/mmcblk1 seek=512 count=256
dd if=/run/media/mmcblk0p1/u-boot.img of=/dev/mmcblk1 seek=768 count=10244864

If rootfs.ext4 is larger than the size of the DDR3, it can only be flashed in Linux. The default rootfs.ext4 for BSP-Yocto-TISDK-AM57xx-PD18PD19.21.0 is larger than the default DDR3 size (2GB).