Bug#707831: UUID detection code broken, wrongly uses UUID

[Colin Watson]

On Sat, May 11, 2013 at 05:28:34PM +0200, Daniel Pocock wrote:
> /etc/grub.d/10_linux wrongly adds root=UUID entries to grub.cfg if
> grub-probe fails
> 
> Specifically, in one case I observed grub-probe had failed because a new
> disk was added (some months ago) and grub-mkdevicemap had not been run.
>  Users typically see this error in that case:
> 
> 
> /usr/sbin/grub-probe: error: Couldn't find PV pv1. Check your device.map.
> 
> 
> The update-grub script should refuse to write out grub.cfg after such
> failures.  Currently it appears to default to UUID= entries, and if root
> is on LVM, the system is then unbootable.

I think most of this was fixed by this upstream commit, and thus is
fixed in 2.00:

2012-03-28  Vladimir Serbinenko  <phcoder at gmail.com>

        * grub-core/disk/diskfilter.c (grub_diskfilter_memberlist): Degrade
        the error when some elements are missing into a warning.

In other words, it's not that important that this PV is missing; in
other cases it might in theory result in missing modules to access bits
of the VG, but that's not actually going to be true in this case so it's
fine for grub-probe to carry on anyway.

The piece noting that we shouldn't carry on if GRUB is unable to
determine the file system of / remains; after consideration I'm inclined
to agree with it, and I've posted a patch for this upstream.

-- 
Colin Watson                                       [cjwatson at debian.org]