[Mesa-dev] [PATCH 4/4] egl/dri2: add image extension to swrast_core_extensions

[Gurchetan Singh]

Emil,

If I understand you correctly, you're proposing to add the ability to use
the kms_swrast driver in platform_x11.c (the host is a standard Ubuntu box
for the emulator use case, not CrOS) alongside swrast.

In that case, we would need to:

1) Have a dri2_initialize_x11_kms_swrast function that's called when some
environment variable is set instead of dri2_initialize_x11_swrast.
2) dri2_initialize_x11_kms_swrast would need access to the host card fd
(dri_kms_init_screen requires this) and call dri2_load_driver instead of
dri2_load_driver_swrast .
3) Use dri2_loader_extensions instead of swrast_loader_extensions,
dri2_x11_display_vtbl instead dri2_x11_swrast_display_vtbl etc.

I'm having trouble getting this to work, and I was wondering if what I'm
trying to do is what you want.  Attached is the patch I'm trying (it
compiles, but will crash your display).

Regarding the issues with the emulator, I filed a bug based your comments
and the emulator team has started looking at it (see
https://android-review.googlesource.com/#/c/418541/).


On Tue, Jun 20, 2017 at 1:19 AM, Emil Velikov <emil.l.velikov at gmail.com>
wrote:

> On 19 June 2017 at 20:46, Chad Versace <chadversary at chromium.org> wrote:
> > On Thu 15 Jun 2017, Gurchetan Singh wrote:
> >> Emil, would you be fine with leaving the image extension in dri2.c but
> still
> >> adding it as a drisw extension?  That solution would look like:
> >>
> >> [1]https://patchwork.freedesktop.org/patch/154807/
> >
> > Observations:
> >     - src/gallium/state_trackers/dri/dri2.c:dri2ImageExtension
> advertises v15 of __DRI_IMAGE.
> >     - egl_dri2.c requires only v1 of __DRI_IMAGE. Maybe a higher version
> >       is required in practive, but the egl_dri2.c code checks only for
> v1.
> >
> > Questions:
> >     1. All functions implemented in dri2.c:dri2ImageExtensions, do they
> >        under swrast? Honest question, because I'm no expert on
> >        gallium.
> >
> > If question #1 is true, then I see no problem with your latest plan. But
> > maybe Emil does.
> >
> > If question #1 is false, it should be straightforward to implement in
> > drisw.c the small subset of __DRI_IMAGE functions required for v1.
>
> While I haven't checked how much [or well] DRI_IMAGE works with
> swrast, there's no need to actually add it there.
> An alternative is to add kms_swrast support for EGL like we already do
> for GBM, as mentioned earlier [1].
>
> Gents, keep in mind that:
>  - one cannot pull DRM specifics (dri2.c) code within drisw.c, and
>  - DRI_IMAGE pulls DRM specifics, hence adding it into drisw.c is
> again a no-go :-\
>
> FWIW the above architectural split applies for classic drivers as
> well. swrast_dri.so simply cannot depend on anything DRM related.
>
> -Emil
>
> [1] https://lists.freedesktop.org/archives/mesa-dev/2017-June/159519.html
>
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