The GALLIUM option enables gallium (llvm) backed drivers such as for example
the r600 and radeonsi driver.

The VDPAU option enables VDPAU drivers to decode video on the GPU via the
VDPAU library.

The TEXTURE option enables texture-float support. However Silicon Graphics
owns the US Patent #6,650,327 [1]. Use at your own risk!

See docs/patents.txt in the Mesa tarball or the follewing urls:

[1] http://www.google.com/patents/about?id=mIIOAAAAEBAJ&dq=6650327
[2] http://www.opengl.org/registry/specs/ARB/texture_float.txt