Bug#656608: grub2 on sqeeze and bugs triggered by qemu/kvm

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 20.01.2012 14:15, Michael Tokarev wrote:
> Package: grub2
> Version: 1.98+20100804-14+squeeze1
> Severity: wishlist
> Tags: squeeze
>
> Hello.
>
> I've two bugreports reported against qemu-kvm package about
> squeeze virtual machines being unbootable.  These are
> #653068 and #616487.  It all boils down to the following
> message during boot (from #653068):
>
>   Loading Linux 2.6.32-5-amd64 ...
>   unaligned pointer 0x93940002
>   Aborted. Press any key to exit.
>
> After some investigation it turns out this is a problem
> in grub itself, its memory management.  In particular,
> I found this:
>
>   https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/717445
>
> In this bugreport, they found out that later grub versions
> does not show this issue.  This is confirmed by my bureports --
> installing grub from wheezy makes it work.
>
> In the LP#717445 there's a backport of a large commit to
> grub made by Serge Hallyn.  He backported a commit which
> made lots of changes to video subsystem handling, see
>
>   https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/717445/comments/11
>
> I tried the 3 patches against grub in squeeze, had to
> tweak some stuff in there, and can confirm it fixes the
> mentioned problem, which confirms what ubuntu guys
> discovered.
>
> Now, the question.  It is definitely worth to fix this
> bug for squeeze, so it will be actually installable in
> qemu/kvm.  It is obviously not possible to fix it for
> past squeeze releases, so original squeeze will remain
> uninstallable which is sad.  It is not really possible
> to fix it in qemu/kvm because tje behavor - as far as
> I can see - depends on quite some randomness.  And
> finally, the backport of that large patch is, well,
> large and may be too risky for squeeze if it is about
> to fix just qemu/kvm problem.
>
> Any opinions/comments?
The patch in question adds native support of qemu/kvm emulated video 
card and it takes precedence over VBE driver. So it's likely to be a red 
herring altogether. I'd try with a grub.cfg with video_bochs and 
video_cirrus lines removed. I was unable to recreate the bug with latest 
bzr GRUB and just vbe driver so I suppose that the actual fix is another 
commit which is, hopefully, smaller
> For now I'll merge the two mentioned bugreports into
> this one, and mark it with Severity: wishlist.
>
> Thanks,
>
> /mjt
>
>
>
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-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko