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

[H.-R. Oberhage]

Hello,

thank you for your kind and helpful answers.

No including the "bugs" e-mail address in my first reply
was my mistake, I just didn't notice, that there was more than
one address. Shouldn't happen again :-).

On 24.09.2021 15:50, Andy Smith wrote:
> Hello,
> 
> On Fri, Sep 24, 2021 at 03:33:21PM +0200, Hans van Kranenburg wrote:
>> The smallest amount of work to initially get your VM going again is to
>> only install the 64 bit kernel and keep running a 32 bit user land.
> 
> Yep, I have a few 32-bit PV domUs that I run as 64-bit just the
> kernel, works great.

That information helps me a lot!

>> The process to fully change from a 32 to 64 system (in place) is 
>> called
>> 'cross grading'. I found instructions at
>> https://wiki.debian.org/CrossGrading
>> 
>> I never did this myself, though.
> 
> I've done it lots of times but for any non-trivial host you have to
> pretty much be a Debian expert to know how to handle the many
> problems that dpkg will encounter. It takes longer than
> reinstalling and a mistake breaks everything. Not recommended.

I also did it with a few machines some time ago, but I remembered
how cumbersome it was. That's why I asked about a "simple" method :-).
I won't do it (cross grading), if not forced to do so.

>> It should be as simple as changing type="pv" to type="pvh" in the 
>> config
>> file. In Debian, using PVH this is possible since Buster. Also, using
>> the xen variant of grub2 (grub-xen and grub-xen-host) is possible.
> 
> I can confirm that I have a lot of Debian stretch domUs running PVH
> but you do need to install backports kernel in the domU. The 4.9.x
> stretch kernelis too old. You need the 4.19.x one from
> stretch-backports. They boot fine for me with pvhgrub.

This, too, helps me a lot. Thank you. All of the machines in question
here, are on buster or newer - although by upgrading. So no stress
here.

> Cheers,
> Andy

Thanks to both of you, Hans and Andy,
  Ruediger
-- 
Dr. H.-R. Oberhage
Mail: Univ. Duisburg-Essen	E-Mail: oberhage at Uni-Duisburg-Essen.DE
       Fakultaet fuer Physik	ruediger at Theo.Physik.Uni-Duisburg-Essen.DE