From 5cd54c43237f7afec7c44d2a398a7e629df78a7a Mon Sep 17 00:00:00 2001
From: Guanran Wang <guanran928@outlook.com>
Date: Tue, 19 Dec 2023 08:29:37 +0800
Subject: [PATCH] nixos: gaming: gamemode: integrate with offloading

---
 nixos/profiles/opt-in/gaming.nix | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/nixos/profiles/opt-in/gaming.nix b/nixos/profiles/opt-in/gaming.nix
index 9c26fda..5e16ae1 100644
--- a/nixos/profiles/opt-in/gaming.nix
+++ b/nixos/profiles/opt-in/gaming.nix
@@ -1,6 +1,7 @@
 {
   pkgs,
   lib,
+  config,
   ...
 }: {
   myFlake.hardware.accessories.xboxOneController.enable = lib.mkDefault true;
@@ -13,6 +14,18 @@
     };
   };
 
+  # Integrate with NVIDIA Optimus offloading.
+  # https://github.com/FeralInteractive/gamemode#note-for-hybrid-gpu-users
+  # https://github.com/NixOS/nixpkgs/pull/273177
+  environment.sessionVariables = {
+    "GAMEMODERUNEXEC" = let
+      inherit (config.hardware.nvidia.prime) offload;
+    in
+      lib.mkIf
+      (builtins.elem "nvidia" config.services.xserver.videoDrivers || offload.enable || offload.enableOffloadCmd)
+      (lib.mkDefault "nvidia-offload");
+  };
+
   ### https://wiki.archlinux.org/title/Gaming#Improving_performance
   systemd.tmpfiles.rules = [
     #    Path                  Mode UID  GID  Age Argument