I patched Backfire 10.03 to boot from a CD and save data to a USB stick on an x86.  I use mini_fo to overlay the USB stick on top of the CD.  I wrote down the details in my blog:  http://macbruins.wordpress.com/2011/05/ … b-support/

A brief summary of the patches:

1.  after booting from CD, /init loop-mount an ext2 image file, and copies files from rootfs to that mount
2.  it then uses switch_root to change root file system to the ext2 image, and start running /etc/preinit.
3.  /etc/preinit runs block-extroot, which mounts the USB stick, creates the ext2-image/USB overlay, and pivot_root to the overlay.

Feedback, comments, suggestions are appreciated.

William

Interesting !
No binaries ?

Sorry, no binaries, because I don't know what other features should be included.  Also, I don't have anything like a public-accessible FTP account.

I can help or compile something for you if you're having trouble.

William