Utah GLX

Utah GLX was a project aimed at creating a fully free and open-source basic hardware-accelerated 3D rendering using the OpenGL rendering API on Linux kernel-based operating systems. Utah GLX predates Direct Rendering Infrastructure, which is what is used as of 2014.

John D. Carmack worked on Utah GLX.

2D drivers inside of the X server

Indirect rendering over GLX, using Utah GLX

Finally all access goes through the Direct Rendering Manager

In Linux kernel 3.12 render nodes were merged and the KMS driver was split of. implements direct rendering over EGL/GBM