[Pkg-xen-devel] Bug#994870: Bug#994870: Bug#994870: Bug#994870: Memory allocation problem for VM after xen security update

[Andy Smith]

Hi Alex,

On Thu, Sep 30, 2021 at 12:10:32AM +0200, Alexander Dahl wrote:
> Am 22.09.21 um 20:54 schrieb Hans van Kranenburg:
> > At this point I would really recommend to not wait for a fix to arrive
> > which makes it start again, but change your VM to use a 64-bit kernel.
> 
> How?

This was answered in earlier comments on this bug; please see:

    https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=994870#15
    https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=994870#20

The brief summary is, "start out like a crossgrade, but only do the
kernel". Very simple and quite safe.

You haven't said how you boot your guest though (show us your
/etc/xen/guest.cfg file). If it's pvgrub, that has a 32-bit and a
64-bit version so you'll need to change those as well. If it's
pygrub you probably don't need to do anything, though pygrub has its
own issues outside the scope of this bug.

> FWIW, Debian 10 VMs with 32 bit running with PVH work fine. My important VM
> is still Debian 9 however due to a software I can not simply upgrade.

I've found PVH needs at least 4.19 guest kernel to work, which can
be achieved in Debian 9 (stretch) today by using kernel from
stretch-backports, so perhaps that is an option for you.

Cheers,
Andy