Which mtdblock contains the NAND rootfs can be determined by
$ cat /proc/mtd
(Actually, the output should remind you of a certain Uboot definition either you or the alpha-6 loader set earlier.)
There is a thread on this forum that describes in detail how to mount a ubi fs, but I don't have the time to run it down right now. Basically, it involves issuing the following commands:
# ubiattach /dev/ubi_ctrl -m 1 -d 0 ## e.g. device 0 on mtd1
# mount -t ubifs ubi0:rootfs /mnt/nand
I'm willing to bet, though, that the rootfs that came with the Plug doesn't have the ubiattach
command on it, nor does it support a /dev/ubi_ctrl device.
So, what you'll probably need to do is reconfigure your Plug to boot using the root fs on the NAND (but DON'T do a saveenv
), and after booting, mount the SDcard's fs from that environment. You can then either copy the current root over wholesale, or copy what you need. When you're done, reboot (and since you didn't do a saveenv
, it should revert back to booting from the SDcard again).
I'd advocate going with the alpha-6's rootfs and reapplying to it any changes you've previously made. I suspect things will always be a bit snarky if you continue to use Plug's original FS with the Ubuntu kernels going forward.