Update firmware with a custom image

[James Cameron]

The normal firmware upgrade method that Daniel describes occurs after
operating system install, but before first boot of the operating
system ... provided external power is available.  After the firmware
upgrade, the next boot occurs automatically and the operating system
takes control.

I can imagine situations where firmware should be updated before
operating system install, but we tried to avoid them during
development.  The scenarios include:

- use of fs0.zip and fs1.zip on same USB drive, (very old XO-1
  firmware does not look for fs0.zip); workaround is to copy fs0.zip
  to fs.zip,

- now fixed firmware bugs that prevent copy-nand or fs-update
  completion.

It doesn't include scenarios of USB drive incompatibility, since the
fixed bugs in that realm would also prevent automatic firmware upgrade
from a USB drive.

If you have scenario where operating system must have later firmware
version for successful use, then you must also ensure external power
is connected on first boot.

-- 
James Cameron
http://quozl.linux.org.au/