make kernel builder callPackage'able

kernel/default.nix

@@ -0,0 +1,43 @@
+{
+  callPackage
+, buildPackages
+, stdenvNoCC
+, fetchFromGitHub
+
+, config
+}:
+let
+  source = fetchFromGitHub {
+    owner = "torvalds";
+    repo = "linux";
+    rev = "3d7cb6b04c3f3115719235cc6866b10326de34cd";  # v5.19
+    hash = "sha256-OVsIRScAnrPleW1vbczRAj5L/SGGht2+GnvZJClMUu4=";
+  };
+
+  # The kernel is huge and takes a long time just to
+  # download and unpack. This derivation creates
+  # a source tree in a suitable shape to build from -
+  # today it just patches some scripts but as we add
+  # support for boards/SoCs we expect the scope of
+  # "pre-treatment" to grow
+
+  tree = stdenvNoCC.mkDerivation {
+    name = "spindled-kernel-tree";
+    src = source;
+    phases = [ "unpackPhase" "patchScripts" "installPhase" ];
+    patchScripts = ''
+      patchShebangs scripts/
+      # substituteInPlace Makefile --replace /bin/pwd ${buildPackages.pkgs.coreutils}/bin/pwd
+    '';
+    installPhase = ''
+      mkdir -p $out
+      cp -a . $out
+    '';
+  };
+in
+{
+  vmlinux = callPackage ./vmlinux.nix {
+    inherit tree;
+    inherit config;
+  };
+}

kernel/vmlinux.nix

@@ -0,0 +1,90 @@
+{  stdenv
+ , buildPackages
+ , runCommand
+ , writeText
+ , lib
+
+ , config
+ , checkedConfig ? {}
+ , tree
+} :
+let writeConfig = name : config: writeText name
+        (builtins.concatStringsSep
+          "\n"
+          (lib.mapAttrsToList
+            (name: value: (if value == "n" then "# CONFIG_${name} is not set" else "CONFIG_${name}=${value}"))
+            config
+          ));
+    kconfigFile = writeConfig "nixwrt_kconfig" config;
+    checkedConfigFile = writeConfig "checked_kconfig" checkedConfig ;
+    inherit lib; in
+stdenv.mkDerivation rec {
+  name = "vmlinux";
+
+  hardeningDisable = ["all"];
+  nativeBuildInputs = [buildPackages.stdenv.cc] ++
+                      (with buildPackages.pkgs;
+                        [rsync bc bison flex pkgconfig openssl ncurses.all perl]);
+  CC = "${stdenv.cc.bintools.targetPrefix}gcc";
+  HOSTCC = "gcc -I${buildPackages.pkgs.openssl}/include -I${buildPackages.pkgs.ncurses}/include";
+  HOST_EXTRACFLAGS = "-I${buildPackages.pkgs.openssl.dev}/include -L${buildPackages.pkgs.openssl.out}/lib -L${buildPackages.pkgs.ncurses.out}/lib " ;
+  PKG_CONFIG_PATH = "./pkgconfig";
+  CROSS_COMPILE = stdenv.cc.bintools.targetPrefix;
+  ARCH = "mips";  # kernel uses "mips" here for both mips and mipsel
+  dontStrip = true;
+  dontPatchELF = true;
+  outputs = ["out"  "modulesupport"];
+  phases = ["butcherPkgconfig"
+#            "patchScripts"
+            "configurePhase"
+            "checkConfigurationPhase"
+            "buildPhase"
+            "installPhase"
+           ];
+
+  # this is here to work around what I think is a bug in nixpkgs packaging
+  # of ncurses: it installs pkg-config data files which don't produce
+  # any -L options when queried with "pkg-config --lib ncurses".  For a
+  # regular nixwrt compilation you'll never even notice, this only becomes
+  # an issue if you do a nix-shell in this derivation and expect "make nconfig"
+  # to work.
+  butcherPkgconfig = ''
+    cp -r ${buildPackages.pkgs.ncurses.dev}/lib/pkgconfig .
+    chmod +w pkgconfig pkgconfig/*.pc
+    for i in pkgconfig/*.pc; do test -f $i && sed -i 's/^Libs:/Libs: -L''${libdir} /'  $i;done
+  '';
+
+  # patchScripts = ''
+  #   patchShebangs --build scripts/
+  # '';
+
+  configurePhase = ''
+    export KBUILD_OUTPUT=`pwd`
+    cp ${kconfigFile} .config
+    cp ${kconfigFile} .config.orig
+    ( cd ${tree} && make V=1 olddefconfig )
+  '';
+
+  checkConfigurationPhase = ''
+    echo Checking required config items:
+    if comm -2 -3 <(grep 'CONFIG' ${checkedConfigFile} |sort) <(grep 'CONFIG' .config|sort) |grep '.'    ; then
+      echo -e "^^^ Some configuration lost :-(\nPerhaps you have mutually incompatible settings, or have disabled options on which these depend.\n"
+      exit 0
+    fi
+    echo "OK"
+  '';
+
+  KBUILD_BUILD_HOST = "nixwrt.builder";
+  buildPhase = ''
+    make -C ${tree} vmlinux
+  '';
+
+  installPhase = ''
+    ${CROSS_COMPILE}strip -d vmlinux
+    cp vmlinux $out
+    make clean
+    mkdir -p $modulesupport
+    cp -a . $modulesupport
+  '';
+
+}