While Intel has long backed an open-source graphics driver for their integrated graphics driver, it was not up until last year when Intel released the i965/G35 documentation that there was public, NDA-free documentation concerning their newer IGPs. Later that year they then released the GMA X4500HD series and since then we have been waiting for them to push out public documentation concerning their G45 chipset. Well, Intel has finally come to the table with this documentation and it is very extensive. This documentation drop today is split into several volumes and makes up well over 1,000 pages of Intel hardware documentation and register descriptions that are available under the Creative Common Attribution, No Derivative Works license.
Angela Gill of Intel's Visual Computing Group and Keith Packard of their Open-Source Technology Center announced the release of the Intel G45 programmer's reference manual on the X.Org mailing list. This documentation, which is available via the Intel Linux Graphics web-site, describes:
"The PRM describes the architectural behavior and programming environment of the chipset and graphics devices. The GMCH’s Graphics Controller (GC) contains an extensive set of registers and instructions for configuration, 2D, 3D, and Video systems. The PRM describes the register, instruction, and memory interfaces and the device behaviors as controlled and observed through those interfaces. The PRM also describes the registers and instructions and provides detailed bit/field descriptions. This information is critical to the development and maintenance of Intel graphics drivers for this hardware."
The G45 Express Chipset documentation is split into four volumes and the first volume is made of up two parts. The volumes include the G45 graphics core, 3D/Media, display registers, and subsystem and cores. Volume 1a of the G45 graphics core documentation is 386 pages, 1b is 234 pages, the 3D/Media documentation is 460 pages, the display register section is 420 pages, and the final volume is likely another several hundred pages, but it currently is missing from their web server. While this documentation covers the G45, not all of the information is new. Some of it is simply revised from the 965/G35 documentation released back in January of 2008 where there are similarities between the IGPs. Additionally, this documentation is marked for January 2009, but it was just publicly released today (likely due to the time needed to clear Intel's legal department).
Cheers to Intel on releasing all of this documentation and register specifications for the G45 IGPs. On a separate but important note, nothing has yet improved in the Intel Poulsbo scene with its Linux driver being binary-only and is currently a bloody mess with its kernel DRM being rejected.