Files
nix-config/modules/nixos/hardware/npu/default.nix
mjallen18 70002a19e2 hmm
2026-04-07 18:39:42 -05:00

104 lines
4.4 KiB
Nix
Executable File

{
lib,
pkgs,
config,
namespace,
...
}:
with lib;
let
inherit (lib.${namespace}) mkBoolOpt;
cfg = config.${namespace}.hardware.npu;
in
{
# AMD XDNA 2 NPU support module.
#
# Enables the amdxdna kernel driver and installs the XRT userspace runtime
# (libxrt_coreutil + the XDNA shim plugin) built from packages/xrt.
#
# Prerequisites:
# • Linux >= 6.14 (amdxdna in-tree) OR linux-firmware >= 20260221
# for the NPU firmware blobs. CachyOS kernels >= 6.14 satisfy this.
# • AMD XDNA 2 NPU silicon (Strix Point, Strix Halo, Kraken Point,
# Gorgon Point — Ryzen AI 300-series and later).
#
# What this module does:
# 1. Installs xrt (libxrt_coreutil, libxrt_driver_xdna, xrt-smi) from
# the local flake package.
# 2. Loads the amdxdna kernel driver.
# 3. Raises the per-process memlock limit (required for NPU DMA buffers).
# 4. Optionally installs fastflowlm and exposes it system-wide.
#
# Usage (NixOS config):
# ${namespace}.hardware.npu.enable = true;
# # Enable FLM system-wide if you also run the lemonade service:
# ${namespace}.hardware.npu.fastflowlm.enable = true;
options.${namespace}.hardware.npu = {
enable = mkEnableOption "AMD XDNA 2 NPU support (XRT + amdxdna driver)";
fastflowlm.enable = mkBoolOpt false ''
Install FastFlowLM (flm) system-wide.
FastFlowLM runs LLMs directly on the AMD XDNA 2 NPU.
Enable this when you also run the lemonade service with an NPU backend,
or want standalone `flm` access.
'';
};
config = mkIf cfg.enable {
assertions = [
{
assertion = pkgs.stdenv.hostPlatform.isx86_64;
message = "${namespace}.hardware.npu: AMD XDNA NPU support is only available on x86_64-linux.";
}
];
# ── Kernel driver ──────────────────────────────────────────────────────
# amdxdna is built-in since Linux 6.14. On older kernels (e.g. CachyOS
# 6.12/6.13) this explicit load request triggers the DKMS module if it is
# installed, or is silently ignored if the driver is already built-in.
boot.kernelModules = [ "amdxdna" ];
# ── XRT userspace runtime ──────────────────────────────────────────────
environment.systemPackages = [
pkgs.${namespace}.xrt
]
++ lib.optional cfg.fastflowlm.enable pkgs.${namespace}.fastflowlm;
# ── Memlock limit ──────────────────────────────────────────────────────
# NPU workloads require locking large memory regions for DMA.
# Without unlimited memlock the NPU will refuse to allocate buffers.
security.pam.loginLimits = [
{
domain = "*";
type = "-";
item = "memlock";
value = "unlimited";
}
];
# For system services (e.g. lemonade, fastflowlm) that run under systemd,
# the PAM limit above does not apply — they must set LimitMEMLOCK in their
# unit. We set a system-wide default via systemd.settings so every service
# inherits unlimited memlock unless it explicitly overrides it.
systemd.settings.Manager.DefaultLimitMEMLOCK = "infinity";
# ── NPU device permissions ─────────────────────────────────────────────
# amdxdna exposes the NPU as /dev/accel/accel0 (DRM accelerator device).
# Add a udev rule so members of the "render" group can open it without root.
services.udev.extraRules = ''
# AMD XDNA 2 NPU grant access to the render group
SUBSYSTEM=="accel", KERNEL=="accel*", GROUP="render", MODE="0660"
'';
# Ensure the render group exists.
users.groups.render = { };
# ── Firmware ──────────────────────────────────────────────────────────
# The NPU firmware blobs ship in linux-firmware >= 20260221.
# hardware.enableAllFirmware (set by modules/nixos/hardware/common) already
# pulls in the full firmware set; this is an explicit belt-and-braces note.
hardware.firmware = [ pkgs.linux-firmware ];
};
}