Date: Fri, 2 Jul 2010 00:32:27 +0100
From: Colin Watson <cjwatson@ubuntu.com>
To: The development of GNU GRUB <grub-devel@gnu.org>
Message-ID: <20100701233226.GU21862@riva.ucam.org>
References: <20100602190744.GA4058@rangda.stickybit.se>
	<4C2D07AC.6020006@gmail.com>
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Subject: Re: [PATCH] Fix root device detection for lvm2
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Reply-To: The development of GNU GRUB <grub-devel@gnu.org>

On Thu, Jul 01, 2010 at 11:25:00PM +0200, Vladimir 'φ-coder/phcoder' Serbinenko wrote:
> On 06/02/2010 09:07 PM, sean finney wrote:
> > Index: b/util/grub.d/10_linux.in
> > ===================================================================
> > --- a/util/grub.d/10_linux.in
> > +++ b/util/grub.d/10_linux.in
> > @@ -43,7 +43,8 @@
> >  esac
> >  
> >  if [ "x${GRUB_DEVICE_UUID}" = "x" ] || [ "x${GRUB_DISABLE_LINUX_UUID}" = "xtrue" ] \
> > -    || ! test -e "/dev/disk/by-uuid/${GRUB_DEVICE_UUID}" ; then
> > +    || ! test -e "/dev/disk/by-uuid/${GRUB_DEVICE_UUID}" \
> > +    || [ "`grub-probe -t abstraction --device ${GRUB_DEVICE} | sed -e 's,.*\(lvm\).*,\1,'`" = "lvm"  ] ; then
> >    LINUX_ROOT_DEVICE=${GRUB_DEVICE}
> >  else
> >    LINUX_ROOT_DEVICE=UUID=${GRUB_DEVICE_UUID}
> 
> Applied with some chages. Thanks

The changes seem to have been to simplify the test to:

  [ "x`grub-probe -t abstraction --device ${GRUB_DEVICE}`" = "xlvm"  ]

Unfortunately this is an incorrect simplification.  grub-probe can print
multiple abstractions, and does in the case of e.g. LVM on RAID.  If it
is correct to avoid UUIDs for plain LVM, it is also correct to avoid
them for LVM on RAID.

-- 
Colin Watson                                       [cjwatson@ubuntu.com]