anchor.diff:  else
   
   let
  +  defaultGalliumDrivers =
  +    if (stdenv.isArm || stdenv.isAarch64)
  +    then ["nouveau" "freedreno" "vc4" "etnaviv"]
  +    else ["i915" "ilo" "r300" "r600" "radeonsi" "nouveau"];
  +  defaultDriDrivers =
  +    if (stdenv.isArm || stdenv.isAarch64)
  +    then ["nouveau"]
  +    else ["i915" "i965" "nouveau" "radeon" "r200"];
  +  defaultVulkanDrivers =
  +    if (stdenv.isArm || stdenv.isAarch64)
  +    then []
  +    else ["intel"] ++ lib.optional enableRadv "radeon";
  +in
  +
  +let gallium_ = galliumDrivers; dri_ = driDrivers; vulkan_ = vulkanDrivers; in
  +
  +let
  +  galliumDrivers =
  +    ["svga"]
  +    ++ (if gallium_ == null
  +          then defaultGalliumDrivers
  +          else gallium_)
  +    ++ ["swrast"];
  +  driDrivers =
  +    (if dri_ == null
  +      then defaultDriDrivers
  +      else dri_) ++ ["swrast"];
  +  vulkanDrivers =
  +    if vulkan_ == null
  +    then defaultVulkanDrivers
  +    else vulkan_;
  +in
  +
  +let
     version = "17.0.0";
     branch  = head (splitString "." version);
     driverLink = "/run/opengl-driver" + optionalString stdenv.isi686 "-32";
  
positive.code:     "--with-dri-driverdir=$(drivers)/lib/dri"
      "--with-dri-searchpath=${driverLink}/lib/dri"
      "--with-egl-platforms=x11,wayland,drm"
    ] ++ (if stdenv.isArm || stdenv.isAarch64 then [
        "--with-gallium-drivers=nouveau,freedreno,vc4,etnaviv,swrast"
        "--with-dri-drivers=nouveau,swrast"
    ] else [
        "--with-gallium-drivers=svga,i915,ilo,r300,r600,radeonsi,nouveau,swrast"
        "--with-dri-drivers=i915,i965,nouveau,radeon,r200,swrast"
        ("--with-vulkan-drivers=intel" + optionalString enableRadv ",radeon")
    ]) ++ [
      (enableFeature enableTextureFloats "texture-float")
      (enableFeature grsecEnabled "glx-rts")
      (enableFeature stdenv.isLinux "dri3")
  
negative.code: { stdenv, fetchurl, fetchpatch, lib
  , pkgconfig, intltool, autoreconfHook, substituteAll
  , file, expat, libdrm, xorg, wayland, openssl
  , llvmPackages, libffi, libomxil-bellagio, libva
  