More Radeon Vega Work Lands For LLVM 5.0

Yesterday we saw 100 patches adding Vega support to the Radeon DRM driver as well as 140 patches adding Vega support to RadeonSI Gallium3D. The other big piece of the open-source Linux driver stack for Vega is the AMDGPU LLVM changes.

Back on 18 February is when the Vega/GFX9 changes were published for the AMDGPU LLVM back-end, which is necessary for working 3D accelerated support with AMD GCN+ hardware.

Adding this Vega/GFX9 support was a big addition to LLVM. That work is queued for LLVM 5.0 with the LLVM 4.0 branching took place back in January. Today from Marek we are seeing some more related AMDGPU LLVM commits. So far there were two more commits today affecting buffer descriptor changes and VGPR indexing.

This Vega support will appear in LLVM 5.0 but remains to be seen if it will be back-ported to LLVM 4.0.1 or any 4.0.x point release, which may be unlikely given the size of the code changes. This may complicate the situation for when we'll see more Linux distributions supporting Radeon RX Vega out-of-the-box. LLVM 5.0 likely won't be released until August or September and distributions aren't usually too quick to update to major new releases of LLVM: we might not see LLVM 5 in Ubuntu 17.10, as an example, given their past update rhythm. But at least there should be PPAs and third-party repositories available of Git code. Then for the AMDGPU DRM kernel driver hopefully the Vega and DC code will manage to get merged for Linux 4.12 and then Mesa 17.1~17.2 for the RadeonSI work.

Stay tuned as the Vega Linux support matures and then Linux Radeon RX Vega benchmarks once the hardware is shipping.