On 10/13/26 8:15 PM, Jim Fehlig wrote:
On 10/13/26 7:06 AM, Ben Grande wrote:
Fired on "on_reboot" values "restart" and "destroy", so event listeners can react to this request. The value "destroy" is useful for applications that have routines run between restarts,
It might be useful for your application, but IMO could be very confusing to others. More below...
therefore the reboot event is still fired in this case. If the value is set to "preserve" then it doesn't seem appropriate to fire reboot event.
Resolves: https://github.com/QubesOS/qubes-issues/issues/8196 Signed-off-by: Ben Grande <ben@invisiblethingslab.com> --- docs/formatdomain.rst | 14 +++++++++++--- src/libvirt-domain.c | 4 +++- src/libxl/libxl_domain.c | 4 ++++ 3 files changed, 18 insertions(+), 4 deletions(-)
diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst index e4eb2d9ba3..a5388c5d11 100644 --- a/docs/formatdomain.rst +++ b/docs/formatdomain.rst @@ -2047,9 +2047,17 @@ Each of these states allow for the same four possible actions. The domain will be terminated and then restarted with a new name. (Only supported by the libxl hypervisor driver.) -QEMU/KVM/HVF supports the ``on_poweroff`` and ``on_reboot`` events handling the -``destroy`` and ``restart`` actions, but the combination of ``on_poweroff`` set -to ``restart`` and ``on_reboot`` set to ``destroy`` is forbidden. +QEMU/KVM/HVF/XEN supports the ``on_poweroff`` and ``on_reboot`` events handling +the ``destroy`` and ``restart`` actions, in which case, a notification is +available when the reboot fires, using the event ID +``VIR_DOMAIN_EVENT_ID_REBOOT``.
This sentence is a bit unclear IMO. It groups on_poweroff + on_reboot together, then says "notification is available when the reboot fires". I'd suggest two sentences, with the second one explicitly scoped. E.g.
QEMU/KVM/HVF/XEN supports the on_poweroff and on_reboot events handling the destroy and restart actions. For on_reboot, a notification is available via VIR_DOMAIN_EVENT_ID_REBOOT when the guest-initiated reboot is detected.
+ +Setting ``on_reboot`` to ``destroy``, prevents libvirt from restarting the +domain on its own, thus allowing a VMM that monitors +``VIR_DOMAIN_EVENT_ID_REBOOT``, to run their own stop and start procedures.
This is an unrelated doc improvement and should be a separate patch IMO.
+ +The combination of ``on_poweroff`` set to ``restart`` and ``on_reboot`` set to +``destroy`` is forbidden. The ``on_crash`` event supports these additional actions :since:`since 0.8.4`. diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c index acd9ffc44b..95764ebd2b 100644 --- a/src/libvirt-domain.c +++ b/src/libvirt-domain.c @@ -1779,7 +1779,9 @@ virDomainShutdownFlags(virDomainPtr domain, unsigned int flags) * Note that the guest OS may ignore the request. * Additionally, the hypervisor may check and support the domain * 'on_reboot' XML setting resulting in a domain that shuts down instead - * of rebooting. + * of rebooting. Depending on the hypervisor and 'on_reboot' setting, + * VIR_DOMAIN_EVENT_ID_REBOOT might be emitted. For more information, see + * https://libvirt.org/formatdomain.html#events-configuration * * If @flags is set to zero, then the hypervisor will choose the * method of shutdown it considers best. To have greater control diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c index 51dc3edcc2..ab9df080ac 100644 --- a/src/libxl/libxl_domain.c +++ b/src/libxl/libxl_domain.c @@ -550,10 +550,14 @@ libxlDomainShutdownThread(void *opaque) VIR_DOMAIN_EVENT_STOPPED_SHUTDOWN); switch ((virDomainLifecycleAction) vm->def->onReboot) { case VIR_DOMAIN_LIFECYCLE_ACTION_DESTROY: + virObjectEventStateQueue(driver->domainEventState, + virDomainEventRebootNewFromObj(vm));
This seems misleading to me. An app monitoring these events will receive a REBOOT event, when in fact the domain will be destroyed, right? AFAICT, in this case the qemu driver emits a SHUTDOWN event with detail GUEST
https://gitlab.com/libvirt/libvirt/-/blob/master/src/qemu/qemu_process.c? ref_type=heads#L775
After sending, I noticed the following proposed patch adds a new SHUTDOWN event detail 'VIR_DOMAIN_EVENT_SHUTDOWN_GUEST_RESET' https://lists.libvirt.org/archives/list/devel@lists.libvirt.org/thread/NFMQ3... Sounds appropriate for your use-case, assuming it's possible to detect a guest-initiated reboot/reset. Regards, Jim