On Wednesday, January 21 2009, Forrest Taylor said:
In the iso-to-disk script, one can add an overlay file. However, I
don't see that it is being used at all--livesys does not reference it at
all. It looks like the XO team passes a kernel parameter, but I haven't
seen the code to actually use it.
My assumption is that the overlay file would be the backend storage for
an LVM snapshot. Has anyone actually used an overlay file? Any ideas
on the implementation?
The overlay gets set up in the initramfs, so see mkliveinitrd in the
mkinitrd package. Basically what happens is that instead of creating a
file that's backed by RAM to use as our dm-snapshot device, we set up
dm-snapshot to write to the file on the USB stick instead.
Jeremy