On 11/19/2014 09:06 AM, Michael S. Tsirkin wrote: >>>> This affects QMP right? >>> >>> I think later patches will tell how. CC'ing Eric. >> >> As far as I can tell, this is just correcting a reporting issue; the >> existing QMP commands/events for tracking balloon size will now properly >> account for hotplugged memory. >> >> What I don't know is if this change in semantics will affect any users. >> Libvirt is not yet supporting memory hotplug, so ideally, fixing this >> bug before libvirt uses memory hotplug means libvirt will never have to >> worry about qemu versions that do incorrect reporting. >> >> The alternative is to declare that the existing QMP commands cannot >> change in semantics for the existing members that it reports, and must >> instead report additional dictionary members describing the amount of >> hot-plugged memory, and then require that the client add the numbers >> together itself. That sounds mean to the client, so I'm hoping we don't >> have to go there. > > > IOW you ack this patch for 2.2? >
Is memory hotplug one of the new features in 2.2? If so, then yes, we should get its semantics right from the start (this is a bug fix to avoid a release with broken semantics). On the other hand, if hotplug existed in 2.1, then we already have a release with odd semantics, so delaying this fix until 2.3 and leaving 2.2 with the same odd semantics would not hurt, and it then becomes a judgment call of whether we are rushing in a possibly incomplete solution by trying to get this into 2.2. (Sorry I haven't been following the history of memory hotplug closer) -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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