Bug#627587: grub-pc: grub-probe: error: cannot stat `/dev/root'.

[Colin Watson]

On Sat, May 28, 2011 at 01:51:46PM +0300, Adrian Bunk wrote:
> On Sat, May 28, 2011 at 11:33:37AM +0100, Colin Watson wrote:
> > On Fri, May 27, 2011 at 11:09:21PM +0300, Adrian Bunk wrote:
> > > On Sun, May 22, 2011 at 11:19:06AM +0100, Colin Watson wrote:
> > > > On Sun, May 22, 2011 at 01:02:01PM +0300, Adrian Bunk wrote:
> > > > > grub-probe: error: cannot stat `/dev/root'.
> > > > 
> > > > Looks like #621738, which only affects people without initrds
> > > 
> > > Matched my setup.
> > > 
> > > > (I'm not sure if that's a sufficient condition, but I gather it's a
> > > > necessary condition).  Do you have the most recent udev package
> > > > installed?
> > > 
> > > I did not, and it works after an udev upgrade.
> > > 
> > > It seems that has to be expressed through a Conflicts on older udev 
> > > versions?
> > 
> > (That should be Breaks, nowadays.)
> 
> I'm not sure what exactly is correct here since udev at least has to be 
> configured before grub.

Breaks then - Conflicts says that the two packages (at relevant
versions) can't be unpacked at the same time.  Breaks is to Conflicts as
Depends is to Pre-Depends, roughly.

> > I'm not sure how effective that will be.  After all, the bug only
> > affects users of systemd,
> 
> I don't have systemd installed.

Ah, so #621738 doesn't quite match your setup.  Odd.

> > by the looks of that other bug, and popcon
> > only shows systemd being used by at most 0.2% of the users of grub2, and
> > even then it's only the subset without initrds who are affected.  The
> > rest have no need to upgrade.  Plus, it's not clear to me from that
> > other bug report whether you need to reboot with the new udev or
> > otherwise manually restart udev before the fix is effective,
> 
> My guess is that the restart of udev in it's postinst is enough,
> but that is just a guess.

OK.  We can hope so.

> > and if so then a Conflicts/Breaks would be insufficient anyway; and,
> > by the time grub2 packages with such a change reach testing, a fixed
> > udev might well already be there.
> 
> That won't help people upgrading from squeeze.

I don't really know enough about when this bug was introduced in udev,
really, or whether it's always been there.  Anyway, the Breaks is in
Debian grub2 bzr now, for the next upload.

Thanks,

-- 
Colin Watson                                       [cjwatson at debian.org]