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Intel Skylake & Broxton To Require Graphics Firmware Blobs
Rodrigo Vivi of Intel's Open-Source Technology Center sent in the pull request for landing these binary files into the linux-firmware repository. Up to now there's been no i915 blobs within the linux-firmware tree.
These first i915 DRM firmware blobs are for Skylake and Broxton for the GuC and DMC. DMC in this context is the Display Microcontroller, which is present in Skylake (Gen9) and newer and used within the display engine to save and restore its state when entering into low-power states and then resuming. The DMC is basically saving/restoring display registers across low-power states separate of the kernel.
The GuC engine on Skylake is responsible for workload scheduling on the parallel graphics engines. Intel explained on 01.org, "GuC is designed to perform graphics workload scheduling on the various graphics parallel engines. In this scheduling model, host software submits work through one of the 256 graphics doorbells and this invokes the scheduling operation on the appropriate graphics engine. Scheduling operations include determining which workload to run next, submitting a workload to a command streamer, pre-empting existing workloads running on an engine, monitoring progress and notifying host SW when work is done." This page also seems to indicate that these firmware blobs are required by the DRM driver rather than being an optional add-on.
The license of these firmware blobs also indicate that redistribution is only allowed in binary form without modification. Beyond that, "no reverse engineering, decompilation, or disassembly of this software is permitted."
These new firmware blobs will certainly have some open-source enthusiasts less excited now about Skylake, Broadwell's successor beginning to ship later this year, and Broxton meanwhile is the new Atom SoC built using the Goldmont architecture and will feature Skylake graphics. If there's any good news out of the situation, at least Intel is shipping these firmware files early rather than NVIDIA that with their months-old hardware still hasn't released their GTX 900 Maxwell firmware files needed by the Nouveau driver to provide open-source hardware acceleration. AMD also tends to be timely with the releasing of their necessary binary-only GPU firmware files for the open-source Linux driver.