Older Intel Graphics To Drop From OpenGL 2.1 To 1.4 On Linux

For older Intel i915~i945 graphics hardware, the Linux Mesa driver has exposed OpenGL 2.1 support while under Windows these ~12+ year old integrated graphics have only exposed OpenGL 1.4. Mesa now though might withdraw its OpenGL 2 support by default for older hardware on the i915 driver.

Back in 2013 was this change to Mesa for always enabling at least OpenGL 2.0 when using the i915 driver. The argument for it was "There's no point in shipping a non-GL2 driver today."

That code flipped on ARB_fragment_shader and ARB_occlusion_query by default with those extensions being needed for GL2 but not being properly supported by this old and slow Intel hardware. Now though there's a new patch with plan to revert the behavior so GL2 wouldn't be enabled by default on i915-era hardware, instead having OpenGL 1.4 like with Windows.

The reasoning for dropping from OpenGL 2.1 to OpenGL 1.4 for i915 is due to Chrome and other applications using really slow code-paths with these newer extensions available and thus provide a worse experience. There have also been Wine issues and other problems.

Once this patch lands though there will be DRI configuration options for enabling the flakey ARB_occlusion_query and ARB_fragment_shader support for i915 if there are particular games/applications where this ends up working right on the older Intel hardware, but otherwise it will be advertising OpenGL 1.4 like users find on Windows.