ollama: enable AMD GPU acceleration

modules/services/ollama.nix

@@ -1,4 +1,6 @@
 # ollama: <https://github.com/ollama/ollama>
+# - <https://wiki.nixos.org/wiki/Ollama>
+#
 # use: `ollama run llama3.2`
 # or use a remote session: <https://github.com/ggozad/oterm>
 #
@@ -23,6 +25,13 @@ in
     services.ollama.group = "ollama";
     services.ollama.models = models;
 
+    # these acceleration settings are relevant to `desko`.
+    # docs also suggest nixpkgs needs to be built with `rocmSupport` (which it isn't, by default),
+    # but i still see GPU offload even without that.
+    services.ollama.acceleration = "rocm";  # AMD GPU acceleration
+    services.ollama.rocmOverrideGfx = "10.1.0";  #< `nix-shell -p "rocmPackages.rocminfo" --run "rocminfo" | grep "gfx"`
+    # services.ollama.environmentVariables.HCC_AMDGPU_TARGET = "gfx1010";  # seems to be unnecessary
+
     users.groups.ollama = {};
 
     users.users.ollama = {