Re: [PATCH] hw/qdev-core: Add compatibility for (non)-transitional devs

[Jason Wang]

On Wed, Oct 20, 2021 at 9:31 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Wed, Oct 20, 2021 at 12:56 AM Eduardo Habkost <ehabkost@redhat.com> wrote:
> >
> > On Tue, Oct 19, 2021 at 12:13:17PM -0400, Michael S. Tsirkin wrote:
> > > On Tue, Oct 19, 2021 at 11:29:13AM -0400, Eduardo Habkost wrote:
> > > > On Tue, Oct 19, 2021 at 06:59:09AM -0400, Michael S. Tsirkin wrote:
> > > > > On Tue, Oct 19, 2021 at 11:46:17AM +0100, Stefan Hajnoczi wrote:
> > > > > > On Tue, Oct 12, 2021 at 10:36:01AM +0200, Jean-Louis Dupond wrote:
> > > > > > > Forgot to CC maintainers.
> > > > > >
> > > > > > Also CCing Jason Wang and Michael Tsirkin for VIRTIO.
> > > > > >
> > > > > > Stefan
> > > > >
> > > > > OMG
> > > > > where all compat properties broken all the time?
> > > >
> > > > Compat properties that existed when commit f6e501a28ef9 ("virtio:
> > > > Provide version-specific variants of virtio PCI devices") was
> > > > merged are not broken, because virtio-*-transitional and
> > > > virtio-*-non-transitional were brand new QOM types (so there's no
> > > > compatibility to be kept with old QEMU versions).
> > > >
> > > > Compat properties referencing "virtio-*-pci" instead of
> > > > "virtio-*-pci-base" added after commit f6e501a28ef9 are probably
> > > > broken, yes.
> > > >
> > > > --
> > > > Eduardo
> > >
> > > Oh. So just this one:
> > >     { "virtio-net-pci", "vectors", "3"},
> > >
> > > right?
> >
> > I think so.  That's the only post-4.0 virtio-*-pci compat property I see in
> > hw/core/machine.c.
> >
> > pc.c doesn't have any post-4.0 virtio-*-pci compat props.  I didn't see any
> > virtio compat props on spapr.c and s390-virtio-ccw.c.
> >
> > >
> > > about the patch: how do people feel about virtio specific
> > > stuff in qdev core? Ok by everyone?
> >
> > Not OK, if we have a mechanism to avoid that, already (the
> > "virtio-net-pci-base" type name).  I wonder what we can do to
> > make this kind of mistake less likely, though.
> >
> > Jean-Louis, Jason, does the following fix work?
>
> Yes.
>
> Acked-by: Jason Wang <jasowang@redhat.com>
>
> Thanks
>
> >
> > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> > ---
> > diff --git a/hw/core/machine.c b/hw/core/machine.c
> > index b8d95eec32d..bd9c6156c1a 100644
> > --- a/hw/core/machine.c
> > +++ b/hw/core/machine.c
> > @@ -56,7 +56,7 @@ GlobalProperty hw_compat_5_2[] = {
> >      { "ICH9-LPC", "smm-compat", "on"},
> >      { "PIIX4_PM", "smm-compat", "on"},
> >      { "virtio-blk-device", "report-discard-granularity", "off" },
> > -    { "virtio-net-pci", "vectors", "3"},
> > +    { "virtio-net-pci-base", "vectors", "3"},

Rethink about this, any chance that we can use "virtio-net-pci" as the
base_name? It looks to me this can cause less confusion and consistent
with the existing compat properties.

Thanks

> >  };
> >  const size_t hw_compat_5_2_len = G_N_ELEMENTS(hw_compat_5_2);
> >
> > --
> > Eduardo
> >