The GPU: an Intel Arc B580 on xe

system/hardware/gpu.nix. The machine is an i5-11400 plus an Arc B580 (Battlemage), on the open source xe driver plus Mesa. A SINGLE driver, declarative, with no CUDA.

History

This host once ran an RTX 3050 (proprietary plus CUDA) with a rescue specialisation during the card swap. The Arc was validated (fastfetch, vainfo, xe loaded) and NVIDIA was REMOVED for good, since the destination was always pure Intel. To resurrect NVIDIA, this file's git history has the complete profile.

Ollama runs ON THIS GPU through Vulkan/Mesa ANV, so the Mesa here is a critical path for AI, not only for games. See ollama.md.

The Battlemage requirements are already satisfied: kernel 6.18 (needs >= 6.12), Mesa 25.x (needs

= 24.3), redistributable firmware turned on (system/hardware/hardware.nix). Ref: https://www.phoronix.com/review/intel-arc-b580-graphics-linux

The two boot details

• boot.initrd.kernelModules = [ "xe" ] loads KMS early, so the screen comes up smooth with no black screen.
• reboot=pci. On a hot reboot the Arc may fail to reinitialize and freeze the POST at the ASUS logo. reboot=pci forces a full reset through 0xCF9, so the firmware reinitializes the GPU clean, like a cold boot. If that ever stops sticking, the ladder is bios, efi, acpi, cold.

Do NOT swap extraPackages for pkgs.unstable.*

TESTED AND REJECTED (06/08/2026). These .so files are not normal libs, they are PLUGINS loaded impurely from /run/opengl-driver/lib by a loader that comes from the STABLE channel, and the loader accepts a driver EQUAL to or OLDER than itself, never newer.

Concretely: libva scans __vaDriverInit_1_<minor> from ITS minor down to 1_0. unstable's iHD exports 1_24 and stable's libva 2.23 only tries up to 1_23, so vaInitialize failed and all decode/encode falls back to the CPU, in silence.

This is the general shape of the version strategy's third layer; see version-bumps.md.

Mesa is a measured exception

MESA is NOT covered by that rule, and this is measured, not a guess: libgbm is a separate package (a stub) and hardware.graphics.package exists precisely to change Mesa's global version. Tested: unstable.mesa's ICD plus the system's loader gave an Arc B580 with Mesa 26.1.6, with no error.

If it is ever worth it, that is where it goes, with package32 = pkgs.unstable.pkgsi686Linux.mesa, IN THAT ORDER. Today it is not worth it: nixpkgs backports the point release into the release (mesa 26.1.5 vs 26.1.6, and the kernel and linux-firmware are IDENTICAL in both channels). For the kernel the lever is linuxPackages_latest, from stable itself; see system/core/boot.nix.

iris is broken for shader workloads

Mesa's iris, the OpenGL driver, calls abort() when the kernel refuses a batch submission, and on this card any Minecraft shaderpack trips it within two minutes. ANV, the Vulkan driver, is fine, so the escape is MESA_LOADER_DRIVER_OVERRIDE=zink per app rather than system wide. The six coredumps and everything that was ruled out are in curseforge.md.