Comments on: Now running Lenny (and a workaround for a Grub bug)

By: B1 » Blog Archive » Running a custom or distribution kernel on a VPS

B1 » Blog Archive » Running a custom or distribution kernel on a VPS — Thu, 26 Aug 2010 01:16:07 +0000

[...] has a nice tutorial here but I ran into this bug. Where grub throws: grub-probe: error: Cannot find a GRUB drive for /dev/xvda2. This is due to [...]

By: Joachim

Joachim — Wed, 21 Jul 2010 18:44:16 +0000

Bryce, if you want to run very different domU installations it's actually very helpful to use pyGrub since that simplifies maintenance a lot for each domU.

The approach you describe is the para-virt model, but that's not the only way to run Xen.

By: Bryce

Bryce — Fri, 05 Feb 2010 07:44:33 +0000

In a Xen VM you don't need no stinkin' grub. Another way to solve this problem is to remove the local (unused) grub and kernel image. The kernel image that's used comes from Dom0.
# dpkg -P linux-image-2.6.26-2-amd64 linux-image-2.6-amd64 grub
The kernel modules, however, should match Dom0's kernel.

By: alexdb

alexdb — Mon, 07 Dec 2009 16:02:58 +0000

I solved this issue like this:

In the DomU just edit:
/var/lib/dpkg/info/linux-image-2.6.26-2-xen-686.postinst

and put this line in comment:
#command -v update-grub > /dev/null && update-grub

so the postinstall script won't try to update grub too

By: Iain

Iain — Fri, 13 Mar 2009 10:26:03 +0000

Hi Francois,

Sorry, but I think this is a different problem that I don't have any idea how to fix as I have no experience managing a domU

Iain

By: francois

francois — Fri, 13 Mar 2009 10:06:02 +0000

Well i'm lost here…

I tried to debootstrap a 32 bits domU into a 64 bits dom0 under lenny.

debootstrap –arch=i386 –include=libc6-xen,firmware-bnx2,linux-image-2.6.26-1-xen-686,linux-modules-xen-686,linux-image-xen-686,grub –components=main,contrib,non-free lenny /mnt/xen http://ftp2.fr.debian.org/debian

But i have this problem (as you) :
dpkg: error processing linux-image-2.6.26-1-xen-686 (–configure):
subprocess post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of linux-image-xen-686:
linux-image-xen-686 depends on linux-image-2.6.26-1-xen-686; however:
Package linux-image-2.6.26-1-xen-686 is not configured yet.
dpkg: error processing linux-image-xen-686 (–configure):
dependency problems – leaving unconfigured
Errors were encountered while processing:
linux-image-2.6.26-1-xen-686
linux-image-xen-686

I update domU.cfg :
root = '/dev/xvda1 ro'
disk = [
'phy:/dev/xen-lvm/386-disk,xvda1,w',
'phy:/dev/xen-lvm/386-swap,xvda2,w',
]
and domU fstab :
/dev/xvda1 / ext3 defaults 0 1
/dev/xvda2 none swap defaults 0 0
proc /proc proc defaults 0 0

But dpkg –configure -a and update-grub does not generate any files under /boot/grub !!

How to fix that ?

By: Iain

Iain — Tue, 17 Feb 2009 09:50:30 +0000

Thanks ressu. I'll send it to Andy and see what he thinks

By: ressu

ressu — Tue, 17 Feb 2009 06:00:29 +0000

pygrub helps in a lot of ways, but this bug has bitten me in more than one environment already.

There is a better solution for this too, check: http://ressukka.net/blog/posts/20090217_Xen_domU_upgrades/

By: Iain

Iain — Mon, 16 Feb 2009 21:44:31 +0000

It's the way the VM came set up. (it's PyGrub actually). I could have removed it but I wanted to be able to easily fall back to etch's kernel if something didn't work.

By: khanku

khanku — Mon, 16 Feb 2009 21:34:38 +0000

What for do you have grub installed in a xen domU exactly?
It isn't necessary and only brings trouble, as you show in this post.