nixpkgs/pkgs/os-specific/linux/kernel/manual-config.nix

{ stdenv, runCommand, nettools, bc, perl, kmod, writeTextFile, ubootChooser }:

let
  readConfig = configfile: import (runCommand "config.nix" {} ''
    echo "{" > "$out"
    while IFS='=' read key val; do
      [ "x''${key#CONFIG_}" != "x$key" ] || continue
      no_firstquote="''${val#\"}";
      echo '  "'"$key"'" = "'"''${no_firstquote%\"}"'";' >> "$out"
    done < "${configfile}"
    echo "}" >> $out
  '').outPath;
in {
  # The kernel version
  version,
  # The version of the kernel module directory
  modDirVersion ? version,
  # The kernel source (tarball, git checkout, etc.)
  src,
  # Any patches
  kernelPatches ? [],
  # Patches for native compiling only
  nativeKernelPatches ? [],
  # Patches for cross compiling only
  crossKernelPatches ? [],
  # The native kernel .config file
  configfile,
  # The cross kernel .config file
  crossConfigfile ? configfile,
  # Manually specified nixexpr representing the config
  # If unspecified, this will be autodetected from the .config
  config ? stdenv.lib.optionalAttrs allowImportFromDerivation (readConfig configfile),
  # Cross-compiling config
  crossConfig ? if allowImportFromDerivation then (readConfig crossConfigfile) else config,
  # Whether to utilize the controversial import-from-derivation feature to parse the config
  allowImportFromDerivation ? false
}:

let
  inherit (stdenv.lib)
    hasAttr getAttr optional optionalString maintainers platforms;

  installkernel = writeTextFile { name = "installkernel"; executable=true; text = ''
    #!${stdenv.shell} -e
    mkdir -p $4
    cp -av $2 $4
    cp -av $3 $4
  ''; };

  commonMakeFlags = [
    "O=$(buildRoot)" "KBUILD_BUILD_VERSION=1-NixOS"
  ];

  drvAttrs = config_: platform: kernelPatches: configfile:
    let
      config = let attrName = attr: "CONFIG_" + attr; in {
        isSet = attr: hasAttr (attrName attr) config;

        getValue = attr: if config.isSet attr then getAttr (attrName attr) config else null;

        isYes = attr: (config.getValue attr) == "y";

        isNo = attr: (config.getValue attr) == "n";

        isModule = attr: (config.getValue attr) == "m";

        isEnabled = attr: (config.isModule attr) || (config.isYes attr);

        isDisabled = attr: (!(config.isSet attr)) || (config.isNo attr);
      } // config_;

      isModular = config.isYes "MODULES";

      installsFirmware = (config.isEnabled "FW_LOADER") &&
        (isModular || (config.isDisabled "FIRMWARE_IN_KERNEL"));

      sourceRoot = stdenv.mkDerivation {
        name = "linux-source-${version}";

        inherit src;

        patches = map (p: p.patch) kernelPatches;

        phases = [ "unpackPhase" "patchPhase" "installPhase" ];

        prePatch = ''
          for mf in $(find -name Makefile -o -name Makefile.include -o -name install.sh); do
              echo "stripping FHS paths in \`$mf'..."
              sed -i "$mf" -e 's|/usr/bin/||g ; s|/bin/||g ; s|/sbin/||g'
          done

          sed -i Makefile -e 's|= depmod|= ${kmod}/sbin/depmod|'

          # Patch kconfig to print "###" after every question so that
          # generate-config.pl from the generic builder can answer them.
          # This only affects oldaskconfig.
          sed -e '/fflush(stdout);/i\printf("###");' -i scripts/kconfig/conf.c
        '';

        installPhase = ''
          cd ..
          mv $sourceRoot $out
        '';
      };
    in {
      outputs = if isModular then [ "out" "dev" ] else null;

      passthru = {
        inherit version modDirVersion config kernelPatches src;
      };

      inherit sourceRoot;

      unpackPhase = ''
        mkdir build
        export buildRoot="$(pwd)/build"
        cd ${sourceRoot}
      '';

      configurePhase = ''
        runHook preConfigure
        ln -sv ${configfile} $buildRoot/.config
        make $makeFlags "''${makeFlagsArray[@]}" oldconfig
        runHook postConfigure
      '';

      buildFlags = [ platform.kernelTarget ] ++ optional isModular "modules";

      installFlags = [
        "INSTALLKERNEL=${installkernel}"
        "INSTALL_PATH=$(out)"
      ] ++ (optional isModular "INSTALL_MOD_PATH=$(out)")
      ++ optional installsFirmware "INSTALL_FW_PATH=$(out)/lib/firmware";

      # Some image types need special install targets (e.g. uImage is installed with make uinstall)
      installTargets = [ (if platform.kernelTarget == "uImage" then "uinstall" else "install") ];

      postInstall = optionalString installsFirmware ''
        mkdir -p $out/lib/firmware
      '' + (if isModular then ''
        make modules_install $makeFlags "''${makeFlagsArray[@]}" \
          $installFlags "''${installFlagsArray[@]}"
        unlink $out/lib/modules/${modDirVersion}/build
        mkdir -p $dev/lib/modules/${modDirVersion}
        mv $out/lib/modules/${modDirVersion}/source $dev/lib/modules/${modDirVersion}/source
        mv $buildRoot $dev/lib/modules/${modDirVersion}/build
      '' else optionalString installsFirmware ''
        make firmware_install $makeFlags "''${makeFlagsArray[@]}" \
          $installFlags "''${installFlagsArray[@]}"
      '');

      postFixup = if isModular then ''
        if [ -z "$dontStrip" ]; then
            find $out -name "*.ko" -print0 | xargs -0 -r ''${crossConfig+$crossConfig-}strip -S
            # Remove all references to the source directory to avoid unneeded
            # runtime dependencies
            find $out -name "*.ko" -print0 | xargs -0 -r sed -i \
              "s|${sourceRoot}|$NIX_STORE/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-${sourceRoot.name}|g"
        fi
      '' else null;

      meta = {
        description =
          "The Linux kernel" +
          (if kernelPatches == [] then "" else
            " (with patches: "
            + stdenv.lib.concatStrings (stdenv.lib.intersperse ", " (map (x: x.name) kernelPatches))
            + ")");
        license = "GPLv2";
        homepage = http://www.kernel.org/;
        maintainers = [
          maintainers.shlevy
        ];
        platforms = platforms.linux;
      };
    };
in

stdenv.mkDerivation ((drvAttrs config stdenv.platform (kernelPatches ++ nativeKernelPatches) configfile) // {
  name = "linux-${version}";

  enableParallelBuilding = true;

  nativeBuildInputs = [ perl bc nettools ] ++ optional (stdenv.platform.uboot != null)
    (ubootChooser stdenv.platform.uboot);

  makeFlags = commonMakeFlags ++ [
    "ARCH=${stdenv.platform.kernelArch}"
  ];

  crossAttrs = let cp = stdenv.cross.platform; in
    (drvAttrs crossConfig cp (kernelPatches ++ crossKernelPatches) crossConfigfile) // {
      makeFlags = commonMakeFlags ++ [
        "ARCH=${cp.kernelArch}"
        "CROSS_COMPILE=$(crossConfig)-"
      ];

      # !!! uboot has messed up cross-compiling, nativeDrv builds arm tools on x86,
      # crossDrv builds x86 tools on x86 (but arm uboot). If this is fixed, uboot
      # can just go into buildInputs (but not nativeBuildInputs since cp.uboot
      # may be different from stdenv.platform.uboot)
      buildInputs = optional (cp.uboot != null) (ubootChooser cp.uboot).crossDrv;
  };
})