It Turns Out AMDGPU KFD Compute Support Can Work On 64-bit ARM

Up to now the AMDKFD kernel driver needed for running the ROCm user-space has only worked on x86_64 CPUs, but with some simple changes, it turns out this Radeon compute kernel driver can work on 64-bit ARM as well.

The motivation for getting the AMDKFD driver working on 64-bit ARM isn't entirely clear so it could be for a reason as simple as an ARM employee discovering it could work fairly trivially or it could be something more interesting. Posted by one the AMDKFD patch wrangler at AMD on Wednesday was this patch allowing the "Kernel Fusion Driver" to build on ARM64 (AArch64). The changes were just a few lines to include allowing the kernel Kconfig option to display for ARM64 and then also dealing with a few x86_64-specific lines of code.

Copied on that patch was Mark Nutter, a principal research engineer at Arm, but no comments in the patch to indicate if there was an ulterior motive for getting AMDKFD working on AArch64.

So far the patch is just sitting on the kernel mailing list and not yet queued, so it's too late for this current cycle. But assuming it's accepted fine, this would then allow the AMDKFD kernel driver to be built on 64-bit ARM should you have a 64-bit ARM board with PCIe x16 connecting to a Radeon GPU and wishing to run GPU compute workloads.