Intel Kabylake Will Still Require Firmware Blobs

Beginning with Skylake and Broxton hardware, Intel began requiring firmware blobs as part of their open-source graphics driver stack. This binary firmware is continuing forward with the next-generation Kabylake processors.

With the in-development Linux 4.5 kernel there is the initial Kabylake support, but that support will be further polished over the next few kernel cycles. Published today was the GuC loading support for Kabylake, The GuC engine is for workload scheduling on parallel graphics engines and is what necessitated the firmware introduction with Skylake and Broxton. So it's not entirely a surprise that there's going to be firmware blobs for Kabylake, it would have been more surprising if they would have dropped it after just one generation.

While the patches today are just for the GuC firmware loading support, it looks like with Kabylake there could be even more firmware blobs required. In one of the mailing list messages it was mentioned, "[an Intel engineer] who is working on some Media features for [Kabylake] that relies on HuC firmware. HuC loading is done by GuC." So with Kabylake there's going to be a HuC too. Digging further, there's HuC patches that were recently published.

The HuC firmware seems related to the HEVC/H.265 video decoding support. One of the code comments for the new HuC code explains, "GEN9 introduces a new dedicated firmware for usage in media HEVC (High Efficiency Video Coding) operations. Userspace can use the firmware capabilities by adding HuC specific commands to batch buffers. On supported platforms, i915's job is to load the firmware stored on the file system and assist with authentication. It is up to userspace to detect the presence of HuC support on a platform, on their own." Given that it's in the proprietary media realm, the HuC blob requires authentication. "The HuC authentication is done by host2guc call. The HuC RSA keys are sent to GuC for authentication."