Re: [libvirt] [Qemu-devel] [PATCH RFC 4/8] target-i386: cpu: consolidate calls of object_property_parse() in x86_cpu_parse_featurestr

On Fri, 3 Jun 2016 09:30:09 +0200 Peter Krempa <pkrempa(a)redhat.com&gt; wrote: > On Thu, Jun 02, 2016 at 18:31:04 +0200, Igor Mammedov wrote: > > On Thu, 2 Jun 2016 17:05:06 +0200 > > Peter Krempa <pkrempa(a)redhat.com&gt; wrote: > > > On Thu, Jun 02, 2016 at 11:53:22 -0300, Eduardo Habkost wrote: > > > > On Thu, Jun 02, 2016 at 02:22:22PM +0200, Igor Mammedov wrote: > > [...] > > > > I couldn't find anything regarding xlevel (so we might actually not > > > support it at all), but we indeed do limit the hv_spinlock count: > > > > > > > > > if (def->hyperv_spinlocks < 0xFFF) { > > > virReportError(VIR_ERR_XML_ERROR, "%s", > > > _("HyperV spinlock retry count must be " > > > "at least 4095")); > > > goto error; > > > } > > > > > > Peter > > Peter, > > Does libvirt still uses -cpu xxx,+feat1,-feat2 syntax > > or canonical property syntax there feat1=on,feat2=off > > We use the legacy one: > > -cpu core2duo,+ds,+acpi,+ht,+tm,+ds_cpl, ... > > and > > -cpu 'qemu32,hv_relaxed,hv_vapic, ... > > for the hyperv features. > > We probably can switch to the new one if there's a reasonable way how to > detect that qemu is supporting the new one. for x86 features became properties since 2.4 release (commit 38e5c119), that's the one way to know it. But it's still only +-features for sparc (that's the last remaining target that has legacy parsing). Another way to detect it is to probe via QOM if CPU has a property corresponding to a feature. Maybe Eduardo knows about other ways to do it.