Mesa Radeon Vulkan Driver "RADV" Works Around Bugs For Unreal Engine 4 & 5

Written by Michael Larabel in Mesa on 15 November 2023 at 08:42 AM EST. 16 Comments
Thanks to prolific Mesa RADV contributor Samuel Pitoiset of Valve's Linux graphics team, a fix is on the way for addressing various issues with Unreal Engine 4 and Unreal Engine 5 games running on Linux.

Going back months have been a variety of bug reports around visual glitches and other on-screen artifacts appearing when running Unreal Engine 5 demos and more. This has been common to Unreal Engine games and using the Mesa Radeon Vulkan driver.

Ultimately it comes down to Unreal Engine relying on uninitialized vRAM and that if making use of RADV's zero vRAM behavior for zeroing out the video memory the rendering issues go away. The behavior to initialize all memory allocated in vRAM as zero can also be set manually via the RADV_DEBUG=zerovram environment variable.

Unreal Engine 5 artifacts

This patch now in Mesa 24.0-devel and marked for back-porting to the Mesa 23.3/23.2 stable series will set the "radv_zero_vram" behavior automatically when running the Unreal Engine as detected by the Vulkan engine name. This one line of XML in turn closes at least a handful of known Mesa RADV bugs. This option has also been used for fixing other game issues with RADV where the games/engine expect their vRAM to be zeroed out.
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