anchor.diff:  
       # Install VirtualBox files
       mkdir -p "$libexec"
  -    find out/linux.*/release/bin -mindepth 1 -maxdepth 1 \
  +    find out/linux.*/${buildType}/bin -mindepth 1 -maxdepth 1 \
         -name src -o -exec cp -avt "$libexec" {} +
   
       # Install kernel modules
  
positive.code: 
    buildPhase = ''
      source env.sh
      kmk
      ${forEachModule "modules"}
    '';
  
  
negative.code: with stdenv.lib;
  
  let
    buildType = "release";
  
    version = "4.3.20"; # changes ./guest-additions as well
  
    forEachModule = action: ''
      for mod in \
        out/linux.*/${buildType}/bin/src/vboxdrv \
        out/linux.*/${buildType}/bin/src/vboxpci \
        out/linux.*/${buildType}/bin/src/vboxnetadp \
        out/linux.*/${buildType}/bin/src/vboxnetflt
      do
        if [ "x$(basename "$mod")" != xvboxdrv -a ! -e "$mod/Module.symvers" ]
        then
          cp -v out/linux.*/${buildType}/bin/src/vboxdrv/Module.symvers \
            "$mod/Module.symvers"
        fi
        INSTALL_MOD_PATH="$out" INSTALL_MOD_DIR=misc \
        make -C "$MODULES_BUILD_DIR" DEPMOD=/do_not_use_depmod \
          "M=\$(PWD)/$mod" BUILD_TYPE="${buildType}" ${action}
      done
    '';
  
  