Re: [QEMU PATCH v5 05/13] virtio-gpu: Configure context init for virglrenderer

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Oct 10, 2023 at 02:41:22PM +0300, Dmitry Osipenko wrote:
> On 9/15/23 14:11, Huang Rui wrote:
> > Configure context init feature flag for virglrenderer.
> > 
> > Originally-by: Antonio Caggiano <antonio.caggiano@collabora.com>
> > Signed-off-by: Huang Rui <ray.huang@amd.com>
> > ---
> > 
> > V4 -> V5:
> >     - Inverted patch 5 and 6 because we should configure
> >       HAVE_VIRGL_CONTEXT_INIT firstly. (Philippe)
> > 
> >  meson.build | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/meson.build b/meson.build
> > index 98e68ef0b1..ff20d3c249 100644
> > --- a/meson.build
> > +++ b/meson.build
> > @@ -1068,6 +1068,10 @@ if not get_option('virglrenderer').auto() or have_system or have_vhost_user_gpu
> >                                         prefix: '#include <virglrenderer.h>',
> >                                         dependencies: virgl))
> >    endif
> > +  config_host_data.set('HAVE_VIRGL_CONTEXT_INIT',
> > +                       cc.has_function('virgl_renderer_context_create_with_flags',
> > +                                       prefix: '#include <virglrenderer.h>',
> > +                                       dependencies: virgl))
> The "cc.has_function" doesn't work properly with PKG_CONFIG_PATH. It ignores the the given pkg and uses system includes. Antonio was aware about that problem [1].
> 
> [1] https://gitlab.freedesktop.org/Fahien/qemu/-/commit/ea1c252a707940983ccce71e92a292b49496bfcd
> 
> Given that virglrenderer 1.0 has been released couple weeks ago,
> can we make the v1.0 a mandatory requirement for qemu and remove
> all the ifdefs? I doubt that anyone is going to test newer qemu
> using older libviglrenderer, all that ifdef code will be bitrotting.

We cannot do that. If is is only weeks old, no distro will
have virglrenderer 1.0 present. QEMU has a defined set of
platforms that it targets compatibility with:

  https://www.qemu.org/docs/master/about/build-platforms.html

For newly added functionality we can set the min version to
something newer than the oldest QEMU target platform.

For existing functionality though, we must not regress wrt
the currently supported set of target platforms. So we can
only bump the min version to that present in the oldest
platform we target.

With regards,
Daniel
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