Radeon RADV Vulkan Driver Tackling NGG Stream-Out

One of the areas the RadeonSI OpenGL and RADV/AMDVLK Vulkan drivers have had a challenging time promptly support with AMD Navi GPUs has been the NGG (Next-Gen Geometry) functionality but it's slowly getting worked out.

The NGG engine support has required various fixes to the graphics drivers, Navi 14 NGG support is borked, and various other Next-Gen Geometry support issues in the Navi driver code. At least on the software side the open-source developers have continued to improve the support and today the latest improvements arrived for the Mesa RADV Vulkan driver.

Samuel Pitoiset of Valve's open-source Linux graphics driver team has now managed to get stream-out functionality working on NGG. Samuel implemented NGG stream-out functionality but the Vulkan transform feedback support is still disabled by default. The problem with the transform feedback support is that it can still randomly hang, similar to NGG issues also seen with the RadeonSI OpenGL driver.

But at least a lot of NGG activity is happening to the Next-Gen Geometry support for Navi/GFX10 so hopefully by the time Mesa 19.3 rolls out in December the support will be in better standing.