On 7/25/25 09:53, Jiri Denemark via Devel wrote:
On Thu, Jul 24, 2025 at 14:39:02 -0400, Collin Walling wrote:
On 7/24/25 03:35, Thomas Huth via Devel wrote:
On 30/06/2025 05.19, Collin Walling wrote:
Changelog
v5 - dropped the "none" test in qemuxmlactivetest (see commit for details) - reordered patches to introduce some tests first, then add qemu.conf changes
v4 - added qemu.conf option to dictate the default behavior for the deprecated_features attribute (Boris) - added qemuxmlactivetests (Boris) - snuck in missing documentation for deprecated_features in formatdomain.rst
v3 - added qemu caps check to avoid breaking s390 guests trying to default deprecated_features='off' on QEMU versions that do not support reporting these features
v2 - changed behavior from disabling features on the host model to instead flagging the guest CPU to disable deprecated features - removed disabling deprecated features on host model in virQEMUCapsInitCPUModelS390 - added flagging deprecated_feats in qemuProcessUpdateGuestCPU - added tests for deprecated_features='on' - split virQEMUCapsUpdateCPUDeprecatedFeatures update and qemuProcessUpdateGuestCPU changes
The intention of reporting deprecated features and modifying the guest CPU model was to alleviate the user from the burden of preparing a guest with the necessary amendments to assure migration to newer hardware. While that goal was met by way of the "deprecated_features='on|off'" attribute, it still adds an extra step that the user must be aware to prepare a guest for migration and the errors that stem from an unsuccessful migration (due to feature incompatibility) is not always clear how to resolve.
These patches make s390 CPU *host models* migration ready from the get-go by introducing a qemu.conf option for disabling deprecated features by default. They may still be disabled for other model types via the respective attribute, or reenabled if desired. The configured behavior may be overridden by explicitly providing the attribute within the guest XML.
The patch series sounds reasonable to me, so FWIW:
Series Acked-by: Thomas Huth <thuth@redhat.com>
Peter, Michal, could we still get this merged for libvirt 11.6 ?
Thomas
Thanks for the Ack and helping to move this along.
I've posted a patch to the list for NEWS mentioning this features in case this series is accepted in time for 11.6.
Both this series and the NEWS patch are pushed now.
Jirka
Thanks! -- Regards, Collin