[Mesa-dev] glxinfo updates?

Ian Romanick idr at freedesktop.org
Thu Aug 30 08:32:15 PDT 2012

On 08/30/2012 02:33 PM, Brian Paul wrote:
> On 08/30/2012 08:08 AM, Ian Romanick wrote:
>> It occurs to me that, even though the i965 driver can support OpenGL
>> 3.1 on some hardware, glxinfo will only (ever) say 3.0. We don't
>> support GL_ARB_compatibility,
> What features of GL_ARB_compatibility are you missing?  Do you plan on
> supporting GL_ARB_compatibility someday?

No.  There are several 3.1 features that interact poorly with some 
compatibility features (especially TexBOs and some legacy texture 
formats).  We'd have to jump through hoops to make some of these 
features at all, and I'd much rather have the time spent optimizing the 
features we do support, finishing OpenGL ES 3.0, and working on OpenGL 3.2

We'd also much rather spend time tuning Mesa and our driver for core 
features than debugging and testing compatibility features that few 
people are likely to use.  You'll notice there there are essentially 
zero piglit tests for compatibility interactions.  I sure don't want to 
tackle that project.

>> so 3.1 isn't backwards compatible with
>> 3.0 or earlier.
>> Should we update glxinfo to try creating a 3.1 context if possible?
> I think so.
>> So
>> far, all future versions of OpenGL are backwards compatible with 3.1.
>> Failing that, should it try 3.2 core, then 3.1, then 1.0 (current
>> behavior)?
> I think so.  I actually started hacking on this a while ago.  Would you
> be interested in a patch if I can find it?

Sure.  It would give me a start, anyway.  One thing I'm struggling with 
is what the default behavior should be and what set of options should be 
available.  I see value to users (and app developers) in still being 
able to see the set of extensions available in pre-3.1 contexts, for 


>> I already anticipate the bug reports of people wondering where 3.1 is
>> when they look at glxinfo output...
> Definitely.
> -Brian

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