thanks i have upgraded version to b256 version . now i can able to do use sd card as bootable root@Omega-BEA9:~# df -h Filesystem Size Used Available Use% Mounted on /dev/root 7.8M 7.8M 0 100% /rom tmpfs 60.9M 96.0K 60.8M 0% /tmp /dev/mmcblk0p1 14.5G 40.3M 13.7G 0% /overlay overlayfs:/overlay 14.5G 40.3M 13.7G 0% / tmpfs 512.0K 0 512.0K 0% /dev /dev/mmcblk0p1 14.5G 40.3M 13.7G 0% /mnt/mmcblk0p1 /dev/mtdblock6 22.1M 708.0K 21.4M 3% /mnt/mtdblock6 /dev/mtdblock7 512.0K 196.0K 316.0K 38% /mnt/mtdblock7