anchor.diff: -{ stdenv, fetchurl, perl, cross ? null }:
  +{ stdenv, fetchurl, cross ? null }:
   
   assert cross == null -> stdenv.isLinux;
   
  
positive.code:        export ARCH=$platform
      fi
      make ${kernelHeadersBaseConfig} SHELL=bash
      make mrproper headers_check SHELL=bash
    '';
  
    installPhase = ''
      make INSTALL_HDR_PATH=$out headers_install
  
      # Some builds (e.g. KVM) want a kernel.release.
      mkdir -p $out/include/config
  
negative.code:     if stdenv.platform ? kernelArch then stdenv.platform.kernelArch else
      abort "don't know what the kernel include directory is called for this platform";
  
    extraIncludeDirs =
      if cross != null then
          (if cross.arch == "powerpc" then ["ppc"] else [])
  