Coreboot: Replacing Intel's Binary Video BIOS Blob

While Intel's the only major graphics hardware vendor to provide a fully open-source and officially-supported Linux graphics driver stack that's accompanied by extensive programming and register documentation, there is still a binary blob -- similar to AMD and their Radeon firmware blobs within the kernel -- when it comes to their video BIOS on the latest Intel hardware.

While some still take issue with binary video BIOS, to most it's really not a problem. However, within the Coreboot project there's been interest in creating a source-based replacement for the video BIOS on Intel's latest-generation Ivy Bridge hardware, such as what's found in the new Samsung Chromebox/Chromebook.

Coreboot developers want minimal graphics support plus source-based start-up code in Coreboot for Ivy Bridge so they can "avoid the issues that come with binary video bioses."

The Intel kernel DRM driver does work fine without a video BIOS having been run to initialize the hardware. A Coreboot developer has now been extracting the kernel driver functions and executing them in user-mode for prototyping Coreboot hardware drivers. This approach has worked for other hardware and now it's almost working for graphics hardware.

Ron Minnich, the developer working on this source-based video BIOS replacement for Ivy Bridge, says I2C is working and he's able to recover the display's EDID and mode. The panel back-light control is working and the GTT can be programmed along with other simple functions, but now he's still working on link training and other functionality. Right now he's troubleshooting these last bits for his source-based video BIOS replacement. "This thing is close, and I feel it is possible, but I've obviously got something wrong."

Details on the work are shared in this Intel mailing list post.