Friday, August 1, 2008

jffs2 to .tar.gz

Milestone 2 of FSO came out a few days ago, but inconveniently for those of us who wish to try it out by booting from a microSD card, there's only a jffs2 image file when what we really want is a tarball of the root filesystem. Sadly, the obvious loopback-mount-the-image-and-tar-it-up trick fails with an error:

MTD: Attempt to mount non-MTD device "/dev/loop0"

Here's a brief howto gleaned from the depths of the 'net:
  • modprobe mtdram total_size=131072 erase_size=128
  • modprobe mtdblock
  • dd if=root.jffs2 of=/dev/mtdblock0
  • mount -t jffs2 /dev/mtdblock0 /mnt
The image itself is only 47M, so I reduced the 131072 (128k) above to 65536(64k) and it of course worked fine.

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