On 07/18/2012 08:02 AM, Luiz Capitulino wrote: > Hi, > > QEMU can now distinguish between S4 and power off for the guest OSes that > suspends to disk through S4. This means that we can have a QMP event for S4 > (so that QMP clients can distinguish between S3 and S4). > > However, as we already emit the SHUTDOWN event for this, it turns out that > there are three different ways of supporting the new event. We could: > > 1. not emit the SHUTDOWN event and only emit the SUSPEND_DISK event > > cons: breaks compatibility, as we'll stop sending an event we send today.
At least the new 'query-events' monitor command will allow libvirt to know which events to listen for; so this is workable. > > 2. emit both, that is, first SUSPEND_DISK and then SHUTDOWN > > cons: emitting two very similar events. This has the most back-compat, but is noisier in that it generates more events. > > 3. extend the SHUTDOWN event to say whether it's a suspend to disk or not, > like this: > > { "event": "SHUTDOWN", "data": { "suspend-to-disk": true }, ... } > > cons: we already have the SUSPEND event, so from an API perspective > it would make sense to have SUSPEND_DISK. > > I prefer item 3, because it seems to be cleanest one. I'm also liking 3, then 1, then 2; but think any of them will work from libvirt's POV. -- Eric Blake ebl...@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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