On Wed, Nov 16, 2016 at 02:15:02PM +0100, Jiri Denemark wrote: > On Tue, Nov 15, 2016 at 11:44:00 -0200, Eduardo Habkost wrote: > > CCing qemu-devel. > > > > CCing Markus, in case he has any insights about the interface > > introspection. > > > > On Tue, Nov 15, 2016 at 08:42:12AM +0100, Jiri Denemark wrote: > > > On Mon, Nov 14, 2016 at 18:02:29 -0200, Eduardo Habkost wrote: > > > > On Mon, Nov 14, 2016 at 02:26:03PM -0500, Collin L. Walling wrote: > > > > > cpu features are passed to the qemu command with feature=on/off > > > > > instead of +/-feature. > > > > > > > > > > Signed-off-by: Collin L. Walling <walling@xxxxxxxxxxxxxxxxxx> > > > > > > > > If I'm not mistaken, the "feature=on|off" syntax was added on > > > > QEMU 2.0.0. Does current libvirt support older QEMU versions? > > > > > > Of course it does. I'd love to switch to feature=on|off, but how can we > > > check if QEMU supports it? We can't really start using this syntax > > > without it. > > > > Actually, I was wrong, this was added in v2.4.0. "feat=on|off" > > needs two things to work (in x86): > > > > * Translation of all "foo=bar" options to QOM property setting. > > This was added in v2.0.0-rc0~162^2 > > * The actual QOM properties for feature names to be present. They > > were added in v2.4.0-rc0~101^2~1 > > > > So you can be sure "feat=on" is supported by checking if the > > feature flags are present in device-list-properties output for > > the CPU model. But device-list-properties is also messy[1]. > > > > Maybe we can use the availability of query-cpu-model-expansion to > > check if we can safely use the new "feat=on|off" system? It's > > easier than taking all the variables above into account. > > Yeah, this could work since s390 already supports > query-cpu-model-expansion. It would cause feature=on|off not to be used > on x86_64 with QEMU older than 2.9.0, but I guess that's not a big deal, > is it? Not a problem, as we have no plans to remove +feat/-feat support in x86 anymore. -- Eduardo -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list