{
  description = "Ivy Bridge Custom Mesa";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
  };

  outputs = { self, nixpkgs }: 
  let
    systems = ["x86_64-linux"];
    
    forAllSystems = f: nixpkgs.lib.genAttrs systems f;
    
    buildCustomMesa = pkgs: pkgs.mesa.overrideAttrs (old: {
      patches = (old.patches or []) ++ [
        ./hd4000-custom.patch
      ];
      mesonFlags = (old.mesonFlags or []) ++ [ "-Dgallium-rusticl=true" ];
    });
    
  in {
    packages = forAllSystems (system:
      let
        pkgs = import nixpkgs { inherit system; };
      in {
        mesa-custom = buildCustomMesa pkgs;
        mesa-custom-32 = buildCustomMesa pkgs.pkgsi686Linux;
      }
    );
  };
}