mobile-nixos.kernel-builder

overlay/mobile-nixos/kernel/builder.nix

@@ -0,0 +1,207 @@
+#
+# mobile-nixos kernel builder
+# ===========================
+#
+# The goal of this kernel builder is to cover most of the kernels with a
+# simpler interface.
+#
+# Since many kernels will be of older vintages, not supported by NixOS'
+# own kernel build infrastructure, this will live as a more limited builder,
+# with the goal of building most kernels supported.
+#
+# It is also an experiments ground for a more ergonomic interface.
+#
+
+{ stdenv
+, path
+, buildPackages
+
+, writeTextFile
+
+, perl
+, bc
+, nettools
+, openssl
+, rsync
+, gmp
+, libmpc
+, mpfr
+
+, libelf
+, utillinux
+
+, bison
+, flex
+}:
+
+let
+  # FIXME : implement some basic rules for most version strings.
+  modDirify = v: v;
+in
+
+{ src
+, version
+, modDirVersion ? modDirify version
+
+, configfile
+# FIXME : Not used anymore...
+, dtb ? null
+, kernelPatches ? []
+, patches ? []
+, postPatch ? ""
+
+# Part of the "API" of the kernel builder.
+# Image builders expect this attribute to know where to find the kernel file.
+, file ? "Image" # FIXME : make more generic?
+
+# FIXME : useful?
+, isModular ? true
+, installsFirmware ? true
+
+}:
+
+let
+  hasDTB = (dtb != null);
+
+  commonMakeFlags = [
+    "O=$(buildRoot)"
+  ]
+  ++ stdenv.lib.optionals (stdenv.hostPlatform.platform ? kernelMakeFlags) stdenv.hostPlatform.platform.kernelMakeFlags
+  ;
+
+  # Path within <nixpkgs> to refer to the kernel build system's file.
+  nixosPath = "${path}/pkgs/os-specific/linux/kernel/";
+
+  # Same installer as in <nixpkgs>, though they don't expose it :/.
+  installkernel = writeTextFile {
+    name = "installkernel";
+    executable=true;
+    text = ''
+      #!${stdenv.shell} -e
+      mkdir -p $4
+      cp -av $2 $4
+      cp -av $3 $4
+    '';
+  };
+
+  # Shortcuts
+  inherit (stdenv.lib) optionals optional optionalString;
+  inherit (stdenv.hostPlatform) platform;
+in
+
+stdenv.mkDerivation {
+  pname = "linux";
+  inherit src version file;
+
+  depsBuildBuild = [ buildPackages.stdenv.cc ];
+  nativeBuildInputs = [ perl bc nettools openssl rsync gmp libmpc mpfr ]
+    ++ optional (stdenv.hostPlatform.platform.kernelTarget == "uImage") buildPackages.ubootTools
+    ++ optional (stdenv.lib.versionAtLeast version "4.14") libelf
+    ++ optional (stdenv.lib.versionAtLeast version "4.15") utillinux
+    ++ optionals (stdenv.lib.versionAtLeast version "4.16") [ bison flex ]
+  ;
+
+  patches =
+    map (p: p.patch) kernelPatches
+    # Required for deterministic builds along with some postPatch magic.
+    ++ optional (stdenv.lib.versionAtLeast version "4.13") "${nixosPath}/randstruct-provide-seed.patch"
+    ++ patches
+  ;
+
+  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|= ${buildPackages.kmod}/bin/depmod|'
+    if [ -e scripts/ld-version.sh ]; then
+      sed -i scripts/ld-version.sh -e "s|/usr/bin/awk|${buildPackages.gawk}/bin/awk|"
+    fi
+  '';
+
+  postPatch = ''
+    # Set randstruct seed to a deterministic but diversified value. Note:
+    # we could have instead patched gen-random-seed.sh to take input from
+    # the buildFlags, but that would require also patching the kernel's
+    # toplevel Makefile to add a variable export. This would be likely to
+    # cause future patch conflicts.
+    if [ -f scripts/gcc-plugins/gen-random-seed.sh ]; then
+      substituteInPlace scripts/gcc-plugins/gen-random-seed.sh \
+        --replace NIXOS_RANDSTRUCT_SEED \
+        $(echo ${src} ${configfile} | sha256sum | cut -d ' ' -f 1 | tr -d '\n')
+    fi
+    ${postPatch}
+  '';
+
+  configurePhase = ''
+    runHook preConfigure
+
+    mkdir build
+    export buildRoot="$(pwd)/build"
+
+    echo "manual-config configurePhase buildRoot=$buildRoot pwd=$PWD"
+
+    if [ -f "$buildRoot/.config" ]; then
+      echo "Could not link $buildRoot/.config : file exists"
+      exit 1
+    fi
+    ln -sv ${configfile} $buildRoot/.config
+
+    # reads the existing .config file and prompts the user for options in
+    # the current kernel source that are not found in the file.
+    make $makeFlags "''${makeFlagsArray[@]}" oldconfig
+    runHook postConfigure
+
+    make $makeFlags "''${makeFlagsArray[@]}" prepare
+    actualModDirVersion="$(cat $buildRoot/include/config/kernel.release)"
+    if [ "$actualModDirVersion" != "${modDirVersion}" ]; then
+      echo "Error: modDirVersion ${modDirVersion} specified in the Nix expression is wrong, it should be: $actualModDirVersion"
+      exit 1
+    fi
+  
+    # Note: we can get rid of this once http://permalink.gmane.org/gmane.linux.kbuild.devel/13800 is merged.
+    buildFlagsArray+=("KBUILD_BUILD_TIMESTAMP=$(date -u -d @$SOURCE_DATE_EPOCH)")
+
+    cd $buildRoot
+  '';
+
+  buildFlags = [
+    "KBUILD_BUILD_VERSION=1-mobile-nixos"
+    platform.kernelTarget
+    "vmlinux"  # for "perf" and things like that
+  ]
+    ++ optional isModular "modules"
+  ;
+
+  installFlags = [
+    "INSTALLKERNEL=${installkernel}"
+    "INSTALL_PATH=$(out)"
+  ]
+    ++ optional isModular "INSTALL_MOD_PATH=$(out)"
+    ++ optional installsFirmware "INSTALL_FW_PATH=$(out)/lib/firmware"
+  ;
+
+  postInstall = ''
+    # Helpful in cases where the kernel isn't built with /proc/config.gz
+    cp -v "$buildRoot/.config" "$out/build.config"
+  '' + optionalString hasDTB ''
+    mkdir -p $out/dtbs/
+    make $makeFlags "''${makeFlagsArray[@]}" dtbs dtbs_install INSTALL_DTBS_PATH=$out/dtbs
+  ''
+  ;
+
+  hardeningDisable = [ "bindnow" "format" "fortify" "stackprotector" "pic" "pie" ];
+
+  # Absolute paths for compilers avoid any PATH-clobbering issues.
+  makeFlags = commonMakeFlags ++ [
+    "CC=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}cc"
+    "HOSTCC=${buildPackages.stdenv.cc}/bin/${buildPackages.stdenv.cc.targetPrefix}cc"
+    "ARCH=${stdenv.hostPlatform.platform.kernelArch}"
+  ] ++ stdenv.lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) [
+    "CROSS_COMPILE=${stdenv.cc.targetPrefix}"
+  ];
+
+  requiredSystemFeatures = [ "big-parallel" ];
+  enableParallelBuilding = true;
+  dontStrip = true;
+}

overlay/overlay.nix

@@ -85,4 +85,13 @@ in
         input: input != self.valgrind-light
       ) oldAttrs.buildInputs;
     });
+
+    # Things specific to mobile-nixos.
+    # Not necessarily internals, but they probably won't go into <nixpkgs>.
+    mobile-nixos = {
+      kernel-builder = callPackage ./mobile-nixos/kernel/builder.nix {};
+      kernel-builder-gcc6 = callPackage ./mobile-nixos/kernel/builder.nix {
+        stdenv = with self; overrideCC stdenv buildPackages.gcc6;
+      };
+    };
  }

systems/bootimg.nix

@@ -1,20 +1,15 @@
-{
-  device_config
-  , initrd
-  , pkgs
+{ device_config
+, initrd
+, pkgs
 }:
 let
   inherit (pkgs) buildPackages;
-in
-let
+  inherit (device_info) kernel dtb;
   device_name = device_config.name;
   device_info = device_config.info;
-  with_qcdt = device_info ? bootimg_qcdt && device_info.bootimg_qcdt;
-  linux = device_info.kernel;
-  kernel = ''${linux}/${linux.image}'';
 
-  # TODO : make configurable
-  dt = "${linux}/boot/dt.img";
+  with_qcdt = device_info ? bootimg_qcdt && device_info.bootimg_qcdt;
+  kernel_file = if device_info ? kernel_file then device_info.kernel_file else "${kernel}/${kernel.file}";
 
   # TODO : Allow appending / prepending
   cmdline = device_info.kernel_cmdline;
@@ -30,20 +25,16 @@ pkgs.stdenv.mkDerivation {
     buildPackages.dtbTool
   ];
 
-  buildInputs = [
-    linux
-  ];
-
   installPhase = ''
-	echo Using kernel: ${kernel}
+	echo Using kernel: ${kernel_file}
 (
 PS4=" $ "
 set -x
     mkbootimg \
-      --kernel  ${kernel} \
+      --kernel  ${kernel_file} \
       ${
         if with_qcdt then
-          "--dt ${dt}"
+          "--dt ${dtb}"
         else
           ""
       } \