Re: [Qemu-devel] [PATCH v2] i386: Add new Hygon 'Dhyana' CPU model

[Pu Wen]

On 2019/4/16 16:19, Daniel P. Berrangé wrote:
> On Tue, Apr 16, 2019 at 02:56:12PM +0800, Pu Wen wrote:
> > On 2019/4/15 17:25, Daniel P. Berrangé wrote:
> > > On Sat, Apr 13, 2019 at 10:54:40AM +0800, Pu Wen wrote:
> > > > @@ -152,6 +154,7 @@ GlobalProperty pc_compat_2_12[] = {
> > > >        { TYPE_X86_CPU, "topoext", "off" },
> > > >        { "EPYC-" TYPE_X86_CPU, "xlevel", "0x8000000a" },
> > > >        { "EPYC-IBPB-" TYPE_X86_CPU, "xlevel", "0x8000000a" },
> > > > +    { "Dhyana-" TYPE_X86_CPU, "xlevel", "0x8000000a" },
> > > >    };
> > > >    const size_t pc_compat_2_12_len = G_N_ELEMENTS(pc_compat_2_12);
> > >
> > > You can drop the changes in this file. This CPU model didn't exist
> > > in any older QEMU releases, so there's no machine type backcompat
> > > required, at least from upstream QEMU POV.
> >
> > Then how about running QEMU with the parameter like "-M pc-i440fx-2.12"?
> > Although the default machine is newer than that.
>
> That doesnt matter.  This back-compat property table is about ensuring
> that "-cpu Skylake-Client -M pc-i440fx-2.12" run on QEMU 4.0.0 release
> works the same way as when run on QEMU 2.12.0 release.
>
> Since there is no Dhyana CPU model in QEMU 2.12.0 release, there's no
> back compat issue to fix.

Thanks for the explanation. Will drop the changes in next version patch.

--
Regards,
Pu Wen