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Re: [libvirt] [PATCH] qemu: Rework handling of shutdown event



On Fri, Dec 02, 2011 at 09:22:37 -0700, Eric Blake wrote:
> On 12/02/2011 08:02 AM, Jiri Denemark wrote:
> > When QEMU guest finishes its shutdown sequence, qemu stops virtual CPUs
> > and when started with -no-shutdown waits for us to kill it using
> > SGITERM. Since QEMU is flushing its internal buffers, some time may pass
> > before QEMU actually dies. We mistakenly used "paused" state (and
> > events) for this which is quite confusing since users may see a domain
> > going to pause while they expect it to shutdown. Since we already have
> > "shutdown" state with "the domain is being shut down" semantics, we
> > should use it for this state.
> > 
> > However, the state didn't have a corresponding event so I created one
> > and called its detail as VIR_DOMAIN_EVENT_SHUTDOWN_FINISHED (guest OS
> > finished its shutdown sequence) with the intent to add
> > VIR_DOMAIN_EVENT_SHUTDOWN_STARTED in the future if we have a
> > sufficiently capable guest agent that can notify us when guest OS starts
> > to shutdown.
> 
> Not for this patch, but should we use VIR_DOMAIN_EVENT_SHUTDOWN_STARTED
> any time we use the virDomainShutdown API to request a graceful
> shutdown?  That is, by actually changing the state of the domain after a
> call to virDomainShutdown, it will be more apparent whether a user has
> previously requested shutdown

Hmm, in that case I would rather introduce another detail
VIR_DOMAIN_EVENT_SHUTDOWN_REQUESTED or something similar so that one can
distinguish between a request that any guest can just ignore and a real
shutdown. And more importantly, we need to decide what state a domain should
be in after virDomainShutdown. IMHO it should still be "running" until we know
the guest is really shutting down. Perhaps a new reason for "running" state
that would mean the domain is running but a shutdown was requested could make
sense.

> ACK.  Up to you whether to fold the examples/ change in now or as a
> followon patch, as long as you remember to do it.

Thanks, I sent a separate patch for adding the event to
examples/domain-events/ and pushed this patch.

Jirka


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