Re: Grub2 with multiple Debians

[Hendrik Boom <hendrik@topoi.pooq.com>]

On Fri, 14 Sep 2012 22:37:28 +0100, Joe wrote:

> On Fri, 14 Sep 2012 20:42:21 +0000 (UTC)
> Hendrik Boom <hendrik@topoi.pooq.com> wrote:
> 
>> On Fri, 14 Sep 2012 23:25:03 +0300, Andrei POPESCU wrote:
>> 
>> > On Vi, 14 sep 12, 17:12:38, Hendrik Boom wrote:
>> >> 
>> >> Of course, after I've made my copy (with slight changes to
>> >> /etc/fstab) I have two nearly identical sets of partitions, so it
>> >> may be tricky to tell them apart.  Is grub2 clever enough to figure
>> >> it all out anyway? And what data does it use to this end? (so I can
>> >> make sure it's right!)
>> > 
>> > UUIDs? What failure mode(s) do you have in mind, because I can't
>> > think of any.
>> 
>> It probably is os-prober that I mean.  The misconfiguration I have in
>> mind is matching one system's /boot with another systems's /.  I've had
>> it happen on a laptop sometime ago. and it sure messed up my upgrades. 
>> I have no idea how it happened, but it has made me paranoid.
>> 
>> 
> The problem is that update-grub rewrites /boot/grub/grub.cfg. It may be
> possible to specify roots and boots in /etc/grub.d/ (I do use a separate
> /boot, but I've never needed to try this) or alternatively it is
> perfectly possible to edit grub.cfg, but you need to remember to do so
> each time update-grub is run, before rebooting. More than once, I've
> known versions of grub not deal correctly with a separate /boot, so I've
> had to do this until the bug was fixed.

It might be that bug that fouled up my laptop.  Or I might have done it 
myself at some point.  Anyway, I've become paranoid about such things.
If the bug has been fixed, well, that'll be one less thing to go wrong 
when I upgrade.

Thanks for telling me that there was a bug, and that it was fixed.

> 
> Both update-grub and grub-mkconfig (which it calls) are scripts and
> possibly some kind of user warning could be appended to one of them.
> 
> Or perhaps if the backup copy were made to a second hard drive (trickier
> with a laptop) then os-prober could be trusted not to mix roots and
> boots between drives.