On 5/26/25 14:40, Peter Krempa via Devel wrote:
On Thu, May 22, 2025 at 02:03:16 -0400, Collin Walling wrote:
To ease the user with defining a guest with a migratable CPU model,
disclaimer: I'm not an expert on: - libvirt's cpu driver - s390x cpu etc.
let's disable the deprecated features from the get-go. If these features are still desired, they may be reenabled via the deprecated_features='on' attribute.
I'd expect that anything that happens with cpu model (as it has guest visible implications [2]) would happen also in XML ...
Some existing tests utilize this updated behavior, so update the CPU features on the corresponding args files.
Signed-off-by: Collin Walling <walling@linux.ibm.com> --- src/qemu/qemu_process.c | 11 +++++++++++ .../default-video-type-s390x.s390x-latest.args | 2 +- ...hostdev-vfio-zpci-ccw-memballoon.s390x-latest.args | 2 +- .../launch-security-s390-pv.s390x-latest.args | 2 +- ...0-default-cpu-kvm-ccw-virtio-4.2.s390x-latest.args | 2 +- .../s390-defaultconsole.s390x-latest.args | 2 +-
... which doesn't seem to be the case as just the .args files changed.
Do the mocked tests perform a cpu model expansion which is done when starting a domain? I tested Collins changes and when dumping the active domain xml the expanded CPU model and also deprecated_features='off' is included if deprecated_features was not already included in the persisted domain xml.
So won't this actually break the guest ABI?
I think Daniel's old email can shed some light on that question. https://lists.libvirt.org/archives/list/devel@lists.libvirt.org/message/MCDG... My understanding is that guest ABI does not include guaranties how a CPU model is expanded and therefore this change does not break the guest ABI. -- Mit freundlichen Grüßen/Kind regards Boris Fiuczynski IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Wolfgang Wendt Geschäftsführung: David Faller Sitz der Gesellschaft: Böblingen Registergericht: Amtsgericht Stuttgart, HRB 243294