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

[Eduardo Habkost]

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?

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