Maybe Alan Cox would be well advised to learn a thing or two about OpenGL licensing before coding a feature that requires a GPL license... because it's essentially useless, no big driver can use it now, and it's not just ATI/Nvidia.
Latest OpenGL 4.3 is not GPL licensed. So he basically coded a feature that no-one can use without releasing all their source under GPL as well. Which means nobody will use it.
Sometimes I wonder if there's like a reality bubble with linux developers... that prevents them from seeing how reality is.. so that stuff like this comes up, where someone codes a GPU feature for modern GPU's (Which all support opengl 4.3) that can not be used at all legally unless these GPU's only support opengl 3.1 (or whatever MESA is stagnating around nowadays)
And OpenGL is just what a noob like me knows... there are probably a dozen other cases like this one in a driver, which make GPL'ing it impossible.
Sidenote: If he didn't code this feature alone, take it as an abstraction.. I was too lazy to check out who coded this specifically.