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

[Igor Mammedov]

On Fri, 3 Jun 2016 09:30:09 +0200
Peter Krempa <address@hidden> 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 <address@hidden> 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.

> 
> Peter
>