Bug#699923: grub-pc fails to upgrade when virtualized device changes type

[Adam Heath]

package: grub-pc
version: 1.99-23.1
severity: important

I use opennebula for virtualization.  I had originaly created a new
image, and installed squeeze to it.  The device mapping I used at the
time exposed this drive as /dev/vda.

Then, I cloned(copied) the image file, and started a new machine.
When I started the new machine, I neglected to set the emulation
correctly, so the drive was seen as /dev/sda.  The machine booted
correctly thru grub and early boot, into squeeze.

The problem came about when I attempted to update to wheezy.  Grub
couldn't reinstall itself, because /boot/grub/device.map had hd0
configured to be /dev/vda.  So grub-install couldn't find the correct
drive mapping for what was now /dev/sda.

Some kind of warning/fix should be detected/applied to device.map in
these cases.

Ideally, a grub upgrade should probably generate a new, temporary
device.map, and compare to the current, and ask if it should be
updated if changed.

ps: Personally, I think this should be fixed before wheezy release.