[PATCH xserver 06/13] glx: Enable GLX_SGI_make_current_read in the core

[Emil Velikov]

On 30 March 2016 at 14:58, Adam Jackson <ajax at redhat.com> wrote:
> On Wed, 2016-03-30 at 12:12 +0100, Emil Velikov wrote:
>> On 23 March 2016 at 22:46, Adam Jackson <ajax at redhat.com> wrote:
>> > diff --git a/glx/glxdri2.c b/glx/glxdri2.c
>> > index c56a376..71dab2a 100644
>> > --- a/glx/glxdri2.c
>> > +++ b/glx/glxdri2.c
>> > @@ -900,13 +900,6 @@ initializeExtensions(__GLXDRIscreen * screen)
>> >      }
>> >
>> >      for (i = 0; extensions[i]; i++) {
>> > -        if (strcmp(extensions[i]->name, __DRI_READ_DRAWABLE) == 0) {
>> > -            __glXEnableExtension(screen->glx_enable_bits,
>> > -                                 "GLX_SGI_make_current_read");
>> > -
>> > -            LogMessage(X_INFO, "AIGLX: enabled GLX_SGI_make_current_read\n");
>> > -        }
>> > -
>> Afaics we never had a DRI2 based dri module that provided this
>> extension. Which brings the question if this has ever been tested and
>> confirmed working. Can we have a small note about this in the commit
>> message ?
>
> Not quite. I am dismayed to report that piglit does not appear to
> contain any tests for separate drawable and readable, so whether this
> has been tested, who knows. And you are correct (and I'm somewhat
> surprised to discover) that Mesa currently does not expose this
> extension. But it used to:
>
> https://cgit.freedesktop.org/mesa/mesa/commit/?id=ad3221587164c10ae16d85db514484b717cabc6f
>
Must have butchered something... the local tree does not go that far in history.

> GLX 1.3 implies equivalent functionality, spelled glXMakeContextCurrent
> instead of glXMakeCurrentReadSGI. The dispatch for both the extension
> and 1.3 versions of the interface has remained wired up in xserver, and
> note that the bindContext call down to the driver _always_ takes both
> drawable and readable arguments regardless of which Make*Current*
> request triggered it.
>
> So I don't think this is making anything any worse.
>
Definitely - make_context_current (and bindContext) have been using
separate readable/drawable since forever. Can you please add some of
the above explanation in the commit history - for posterity.

Thanks
Emil