qemu no-shutdown feature in libvirt

[Luna Xu]

Hi Peter,

Thank you again for replying here. These are great instructions. I
will take a look into these. Thank you!

Thanks,
Luna

On Tue, Dec 1, 2020 at 9:34 AM Peter Krempa <pkrempa at redhat.com> wrote:
>
> On Mon, Nov 30, 2020 at 14:45:18 -0500, Luna Xu wrote:
> > Hi developers,
>
> Hi,
>
> [...]
>
> > When I start a VM with the qemu command I can specify the -no-shutdown
> > flag so that my qemu process doesn't quit even if I shutdown the VM
> > from the inside (issue shutdown or halt command inside VM). The VM is
> > shutdown but the qemu process is not killed so that the jobs I
> > submitted before for example backup (drive-backup) can continue to run
> > even after VM gets shutdown by the user, and I'm able to check the
> > status of the job through qmp commands (by communicating with the qemu
> > process).
>
> As I've noted in my reply on libvirt-users, we currently don't support
> this on the shutdown part of the VM lifecycle.
>
> On the startup part you can use VIR_DOMAIN_START_PAUSED for a VM which
> didn't yet excecute any guest instructions.
>
> > Is anyone aware of any project that is currently implementing this
> > functionality? Thanks for reading.
>
> I don't think that there's anybody working on it.
>
> If you are interested in implementing the feature the idea would be to
> add a 'pause' action for <on_poweroff>pause</on_poweroff> along with a
> new 'virDomainPausedReason' such as VIR_DOMAIN_PAUSED_POWEROFF and
> implement the lifecycle transition from PAUSED -> RUNNING via
> qemuDomainResume, which would in this case have to issue a
> 'system-reset' qmp command and emit the appropriate events.
>