Re: [libvirt] [PATCH v3 3/4] qemu_capabilities: Introduce QEMU_CAPS_PM_WAKEUP_SUPPORT

On 4/11/19 12:12 PM, Daniel Henrique Barboza wrote: > <snip/> > > All that said, I think a good solution would be (2). dompmsuspend isn't a > performance sensitive command, thus the extra time to execute the API > can be ignored. Also, we can still check for > QEMU_CAPS_QUERY_CURRENT_MACHINE > inside qemuDomainPMSuspendForDuration to avoid firing up an error in a > QEMU version that doesn't know the API. That's the thing. We can't. The capability doesn't exist yet. So every domain that is currently running thinks that qemu doesn't have the capability. And when updating libvirt to say next release only freshly started domains might/will have the capability. For all already running domains libvirt thinks the capability is not there. Only freshly started domains will get the capability. IOW, upgrading libvirt won't help you unless you restart your domains (might not want to do that).