AMD Lands A Number Of RadeonSI RDNA NGG Fixes Ahead Of RDNA3 Enabling

Well known AMD Mesa developer Marek Olšák landed more than two dozen patches this weekend fixing up Next-Gen Geometry (NGG) Stream-Out / Transform Feedback functionality for RDNA/RDNA2 GPUs ahead of the NGG Stream-Out enabling for upcoming RDNA3 graphics cards.

Marek has been working to ensure the NGG Stream-Out functionality for existing GFX10-based RDNA1/RDNA2 graphics processors is in good shape before enabling the functionality for GFX11-based RDNA3 graphics.

With the 26 patches merged to Mesa 22.2 there are nine known fixes, including two fixes for hangs stemming from the NGG stream-out / transform feedback functionality. Marek is trying to ensuring "preparation for Gfx11 NGG streamout by stabilizing Gfx10 NGG streamout."

These changes affect the RadeonSI Gallium3D driver though NGG stream-out for RADV was challenging too but seems to have stabilized as well since its wiring up three years ago.

With GFX11/RDNA3 graphics processors, NGG is now always enabled as AMD's "next-gen" geometry engine originally introduced in Vega but only mature enough by time of RDNA2.

See this MR for all the NGG Stream-Out / Transform Feedback fixes ahead of the GFX11/RDNA3 work coming up next.

AMD's open-source Linux graphics driver developers have been very busy with bringing up GFX11 / RDNA3 support ahead of the expected Radeon RX 7000 series graphics cards launching later this year. Right now both the Linux kernel and Mesa RadeonSI (and unofficially, RADV) driver changes remain very active in enabling the new GPU blocks. Hopefully for Mesa 22.2 and Linux 5.20 things will settle down to be in good enough shape for preliminary support.