anchor.diff:  stdenv.mkDerivation {
     name = "perf-linux-${kernel.version}";
   
  -  inherit (kernel) src makeFlags;
  +  inherit (kernel) src;
   
     preConfigure = ''
       cd tools/perf
  
positive.code:       substituteInPlace $x --replace /usr/lib/debug /run/current-system/sw/lib/debug
      done
  
      [ -f bash_completion ] && sed -i 's,^have perf,_have perf,' bash_completion
      export makeFlags="DESTDIR=$out WERROR=0 $makeFlags"
      export NIX_CFLAGS_COMPILE="$NIX_CFLAGS_COMPILE -DTIPDIR=\"$out/share/doc/perf-tip\""
    '';
  
    # perf refers both to newt and slang
    nativeBuildInputs = [ asciidoc xmlto docbook_xsl docbook_xml_dtd_45 libxslt
        flex bison libiberty libaudit makeWrapper pkgconfig python perl ];
    buildInputs =
      [ elfutils newt slang libunwind libbfd zlib openssl systemtap.stapBuild numactl
      ] ++ stdenv.lib.optional withGtk gtk2;
  
    # Note: we don't add elfutils to buildInputs, since it provides a
    # bad `ld' and other stuff.
  
negative.code:       "-Wno-error=bool-compare"
        "-Wno-error=deprecated-declarations"
        "-DOBJDUMP_PATH=\"${binutils}/bin/objdump\""
        "-DTIPDIR=\"$(out)/share/doc/perf-tip\""
      ]
      # gcc before 6 doesn't know these options
      ++ stdenv.lib.optionals (hasPrefix "gcc-6" stdenv.cc.cc.name) [
  