[Mesa-dev] multiple versions in version string

Nathan Kidd nkidd at opentext.com
Mon Jun 20 11:03:15 PDT 2011

On 11-06-20 01:22 PM, tom fogal wrote:
> I am trying to get some regression tests to run in Xvfb.  On my
> workstation, the GL_VERSION string from this is:
>    1.4 (2.1 Mesa 7.7.1)
> according to glxinfo.  The extensions fairly clearly show 2.x features.
> Is it perhaps the case that 2.1 features were available in 7.7.1, but
> not /all/ 2.1 features, and thus this was labelled incorrectly?  The
> version string seems "fixed" in more modern versions.
> In any case, the above version string breaks projects like GLEW
> -- one application I have breaks because GLEW doesn't try to load
> glGenBuffers, thinking it will not be there.  A string like the above
> suggests that GLEW should just try to load whatever it can, and just
> ignore the version string from the library.
> Thoughts?

 From section "3.3.2 GLX Versioning" of the GLX 1.4 spec:

The version string is laid out as follows:

<major version.minor version><space><vendor-specific info>

Both the major and minor portions of the version number are of arbitrary 
length. The vendor-specific information is optional. However, if it is 
present, the format and contents are implementation specific.

So any app that confuses the vendor-specific info for the version 
major.minor has a bug (though one I've seen before).

In the context of debugging problems with indirect GLX those 
parenthetical versions are quite helpful.


                OpenText Connectivity Solutions Group
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