AMDGPU vs. Radeon DRM With Linux 4.14 On GCN 1.0/SI GPUs

It's been a while since last testing the older GCN 1.0 "Southern Islands" graphics cards with the AMDGPU DRM driver rather than the default Radeon DRM driver. Here are some fresh comparison tests using some original GCN graphics cards with the two DRM drivers while pairing it with Mesa 17.4-dev, including Vulkan tests that are made possible by switching over to the AMDGPU Direct Rendering Manager driver.