In the next step towards open-source 3D support for the R500 and R600 GPUs (Radeon X1000 and Radeon HD 2000/3000), AMD has just pushed its production microcode into the Mesa/DRM git tree. This is the microcode found in the fglrx driver and it covers the Radeon R100 to R600 product families.
This microcode dump can be found in the Mesa/DRM git tree in shared-core/radeon_cp.c. This file is made up of the microcode (arrays made up of hex) for the R100, R200, R300, R420, RS600, RS690, R520, R600, RV610, and RV620. In providing this microcode AMD had looked at what is available in tcore and what's in use by their proprietary drivers. The microcode in their drivers was newer, so they decided to push that copy out into the open as their next step towards open-source 3D graphics. For a simple description, microcode is low-level instructions for the graphics processor.
In a second commit today, Alex Deucher has switched the Radeon DRM to taking advantage of this new microcode for the existing Radeon products supported and adding in the code to load this production microcode for the latest ATI graphics products.
Open-source R500/600 3D graphics rendering with Mesa isn't available today, but this microcode availability is the next major step in the right direction for AMD with their open-source philanthropy and enabling the OSS community. This move is coming less than a week after they went back and released their R300 3D register reference guide and they had pushed out their R500 3D programming documentation late last month. We found out a few days ago that AMD will also be releasing ATI R200 documentation as it provides an introductory graphics programming guide that may allow new software developers to get involved with X driver development. Next up on AMD's agenda is providing R600 3D register information and looking at finally releasing tcore.