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

[Michael S. Tsirkin]

On Tue, Oct 19, 2021 at 12:56:11PM -0400, Eduardo Habkost 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?
> 
> 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);

Hmm I'm a bit confused at this point, as to why does
specifying properties for virtio-net-pci on command
line with -global work, but in compat list doesn't. Do others
understand?


> -- 
> Eduardo