Re: xen 4.17.2 qemu-system-i386 crashes

[Chuck Zmudzinski <brchuckz@xxxxxxxxxxxx>]

On 8/18/2023 7:42 PM, xen@xxxxxxxx wrote:
> Am 18.08.23 um 02:32 schrieb Chuck Zmudzinski:
>> On 8/17/23 7:22 PM, xen@xxxxxxxx wrote:
>>> Hello,
>>>
>>> I am using Archlinux. Last month I built and installed xen-4.17.2pre
>>> which works perfectly. Today I built and installed the newly released
>>> xen-4.17.2.
>>> Now qemu-system-i386 crashes.
>>>
>>> I attached an excerpt from the log.
>>>
>> 
>> Hmm. I am on Fedora 38, and they just pushed out the 4.17.2 update to me
>> yesterday and qemu-system-i386 is working fine with it. This is the version
>> info on Fedora 38 that is working:
>> 
>> Xen version info from sudo xl dmesg on Fedora 38:
>> 
>> (XEN) Xen version 4.17.2 (mockbuild@) (gcc (GCC) 13.2.1 20230728 (Red Hat 
>> 13.2.1-1)) debug=n Thu Aug 10 22:11:44 UTC 2023
>> 
>> Qemu version info on Fedora 38:
>> 
>> [user@fedora ~]$ qemu-system-i386 -version
>> QEMU emulator version 7.2.1 (qemu-7.2.1-2.fc38)
>> Copyright (c) 2003-2022 Fabrice Bellard and the QEMU Project developers
>> [user@fedora ~]$
>> 
>> So, I think maybe you are using a different Qemu version that does not
>> work with Xen 4.17.2.

With the new data this suggestion I made yesterday seems wrong now.

> 
> Xen 4.17.2pre runs on this hardware with both Qemu 8.0.2 and Qemu 8.0.4 
> without problems> 
> On older hardware (Intel Haswell processor) Xen 4.17.2 runs without 
> problems with Qemu 8.0.4. Obviously only my newer hardware is affected.

My working result is also on older hardware (Intel Haswell processor) so
we agree the problem you are seeing is related to newer hardware. It
might help to mention the model of processor in your newer hardware.

Unfortunately I do not have newer hardware to test my Qemu 7.2.x with
Xen 4.17.2 so I won't be able to help you out much any more. (Today
Fedora pushed out Qemu 7.2.4 to me and that also works fine with Xen 4.17.2
on the Haswell processor).

With this additional data it seems the changes in Xen (not changes in Qemu)
are causing the core dump in Qemu on the newer hardware. If no one here
on xen-users has any ideas you might try posting this bug on the xen-devel
mailing list instead. Mention Haswell always works, but something goes
bad with Qemu when upgrading from 4.17.2pre to 4.17.2 on the newer
hardware, and mention the model of processor of the newer hardware and
the excerpt from the journal, and maybe some of the developers can help
you troubleshoot the problem. There presumably are not a lot of changes
between Xen 4.17.2pre and 4.17.2 so hopefully the developers can find the
problem and fix it for the next release.

> 
>> What version of Qemu are you using? Is it the one from the qemu-xen repo on
>> xenbits.xen.org, or one provided by Arch? In any case, Qemu 7.2.1 provided
>> by Fedora works fine with the newly released Xen 4.17.2 on my Fedora 38 
>> system.
> 
> I use an AUR package that compiles the latest Qemu from the upstream 
> sources.
> 

Ok, it's not caused by any changes in the qemu-xen repo on xenbits.xen.org then.