anchor.diff:  
       # set the default search path for DRI drivers; used e.g. by X server
       substituteInPlace "$dev/lib/pkgconfig/dri.pc" --replace '$(drivers)' "${driverLink}"
  +  '' + optionalString (!(stdenv.isArm || stdenv.isAarch64)) ''
  +    # move share/vulkan/icd.d/
  +    mv $out/share/ $drivers/
  +    # Update search path used by Vulkan (it's pointing to $out but
  +    # drivers are in $drivers)
  +    for js in $drivers/share/vulkan/icd.d/*.json; do
  +      substituteInPlace "$js" --replace "$out" "$drivers"
  +    done
     '';
   
     # TODO:
  
positive.code:     "--with-dri-driverdir=$(drivers)/lib/dri"
      "--with-dri-searchpath=${driverLink}/lib/dri"
      "--with-egl-platforms=x11,wayland,drm"
    ]
      ++ optionals (stdenv.system != "armv7l-linux") [
        "--with-gallium-drivers=svga,i915,ilo,r300,r600,radeonsi,nouveau,freedreno,swrast"
        "--with-dri-drivers=i915,i965,nouveau,radeon,r200,swrast"
        "--with-vulkan-drivers=intel"
    ]
      ++ [
      (enableFeature enableTextureFloats "texture-float")
      (enableFeature grsecEnabled "glx-rts")
      (enableFeature stdenv.isLinux "dri3")
  
negative.code:       $out/lib/libxatracker* \
        $out/lib/libvulkan_*
  
      mv $out/lib/dri/* $drivers/lib/dri # */
      rmdir "$out/lib/dri"
  
  