AMDKFD Driver Does More Prepping For Carrizo / VI APUs

Written by Michael Larabel in AMD on 13 January 2015 at 09:36 AM EST. 3 Comments
Earlier this month I wrote about AMD preparing open-source HSA support for Carrizo APUs that aren't launching until later this year. Today more patches were published for the AMDKFD kernel driver in preparing for the forthcoming Volcanic Islands APUs.

As explained in the earlier article, Volcanic Islands is the codename for the AMD GCN 1.2 architecture that provides a more efficient ISA, video scaler improvements, a new multimedia decode/encode engine, improved performance, and other optimizations. The Volcanic Islands will come to AMD's APUs with the forthcoming "Carrizo" products. Carrizo will feature the latest GCN graphics while featuring "Excavator" CPU cores, DDR3/DDR4 memory support, and other new features. On the desktop side, the R9 285 Tonga is the first VI GPU.

Prototype Carrizo systems were shown last week at CES in Las Vegas, but the launch isn't expected still for some months. However, due to the kernel development cycle, kernel patches are already coming out to ensure they'll be mainlined in time given AMD's unified Linux driver focus and thus needing to get mainline support for new hardware ASAP.

Oded Gabbay at AMD who has been spearheading the AMDKFD driver work sent four new patches today in preparing the HSA support for the new APUs. "This patch-set continues to prepare amdkfd so it could support VI APU. it prepares DQM [Device Queue Manager] and KQ [Kernel Queue] modules to support more than one ASIC." More work beyond the new patches and the older work is still needed for getting Volcanic Islands fully supported.

On a slightly unrelated note, for those wondering about the name of this new AMDKFD kernel driver, John Bridgman explained it as "KFD is short for Kernel FSA Driver. What we call HSA today used to be called FSA (Fusion System Architecture), but was renamed to make it less AMD-specific as part of ramping up a cross-vendor consortium. There was an internal discussion along the lines of 'we need a term for AMD's HSA implementation so let's use keep FSA for the AMD implementation.' Since the kernel driver was vendor-specific we kept the KFD name rather than renaming it to KHD (and KHD rolls even less smoothly off the tongue than KFD)."

Aside from AMDKFD work for Carrizo, there's already been enablement/optimization work within the open-source compilers for Bdver4 and thermal monitoring code, among other work. One of the big items we're still waiting on though is the premiere of the new AMDGPU DRM driver that will replace the Radeon DRM driver for the Radeon R9 285 and all future AMD graphics processors.
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