On 10/15/26 2:57 AM, Daniel P. Berrangé wrote:
On Wed, Oct 14, 2026 at 10:41:46AM -0600, Jim Fehlig via Devel wrote:
Thanks for the review Michal! Before pushing, I'd like to get opinions on an
idea Claudio and I discussed off-list: a new
VIR_DOMAIN_EVENT_UNDEFINED_MIGRATED detail for the UNDEFINED event.
On 10/14/26 7:26 AM, Michal Prívozník wrote:
On 10/13/26 22:47, Jim Fehlig via Devel wrote:
From: Jim Fehlig <[email protected]>
When migrating with VIR_MIGRATE_UNDEFINE_SOURCE, qemuMigrationSrcConfirm()
and qemuMigrationSrcPerformJob() delete the domain's persistent config on
the source host but never emit a VIR_DOMAIN_EVENT_UNDEFINED lifecycle
event. Applications relying solely on domain events never learn the domain
was undefined on the source. Emit the event, reusing the existing
VIR_DOMAIN_EVENT_UNDEFINED_REMOVED detail since the semantics match
virDomainUndefine().
While the semantics are the same within libvirt (virDomainDeleteConfig;
vm->persistent=0;), the distinction between UNDEFINED_REMOVED and
UNDEFINED_MIGRATED could be important to a platform using libvirt events for
state synchronization. If agreed, I'll respin a V2 adding the new detail.
Yes, I think it deserves a new constant.
The "reason" should always reflect the API call or operation that
/caused/ the lifecycle change to take place.
IMHO "UNDEFINED_REMOVED" corresponds to the explicit virDomainUndefine
API call/operation.
I've sent a V2 that adds UNDEFINED_MIGRATED
https://lists.libvirt.org/archives/list/[email protected]/thread/PKRALGECT2BUVBQYXV3QNVJMSGXO7R3F/
We use "MIGRATED" as a reason for most other lifecycle events:
$ grep _MIGRATED include/libvirt/libvirt-domain.h
VIR_DOMAIN_RUNNING_MIGRATED = 2, /* migrated from another host
(Since: 0.9.2) */
VIR_DOMAIN_SHUTOFF_MIGRATED = 4, /* migrated to another host (Since:
0.9.2) */
VIR_DOMAIN_EVENT_STARTED_MIGRATED = 1, /* Incoming migration from another
host (Since: 0.5.0) */
VIR_DOMAIN_EVENT_SUSPENDED_MIGRATED = 1, /* Suspended for offline
migration (Since: 0.5.0) */
VIR_DOMAIN_EVENT_RESUMED_MIGRATED = 1, /* Resumed for completion of
migration (Since: 0.5.0) */
VIR_DOMAIN_EVENT_STOPPED_MIGRATED = 3, /* Migrated off to another host
(Since: 0.5.0) */
and both EVENT_DEFINED and EVENT_UNDEFINED could justify doing
the same.
WRT the VIR_MIGRATE_PERSIST_DEST flag, the qemu driver already emits a DEFINED
event with either VIR_DOMAIN_EVENT_DEFINED_ADDED or
VIR_DOMAIN_EVENT_DEFINED_UPDATED detail. See qemuMigrationDstPersist() in
qemu_migration.c
https://gitlab.com/libvirt/libvirt/-/blob/master/src/qemu/qemu_migration.c?ref_type=heads#L6659
Same for the libxl driver. I think we'd risk app breakage if unconditionally
changing that to VIR_DOMAIN_EVENT_DEFINED_MIGRATED, right?
Regards,
Jim
