Re: [libvirt] [PATCH 0/5] qemu: Detect KVM usability correctly

On Fri, Sep 14, 2018 at 15:36:42 +0200, Andrea Bolognani wrote: > How ridiculous would it be to invalidate capabilities whenever > the daemon is restarted? That might strike a somewhat reasonable > balance between requiring the admin to delete a bunch of internal > files after configuring the system to load the KVM module and > re-probing QEMU all the time. This would effectively revert the addition of on-disk cache, which was introduced with a very good reason. Starting libvirtd with a lot of QEMU binaries would take a very long time without the persistent cache. Also libguestfs running libvirt in session mode would get crazy about it. In other words, invalidating capabilities cache whenever libvirtd is started is not acceptable.

> > After removing this capability it looks like virQEMUCapsIsValid will > > always invalidate every single non-native QEMU binary since kvm could > > not clearly be used when probing and /dev/kvm is present. Shouldn't we > > add a check which makes sure we don't go this far for non-native > > binaries? > > We can use virQEMUCapsGuestIsNative() and skip all KVM-related > checks for non-native binaries. Does that sound okay? Yeah, I think that should work.