From bf7467cbb1f08470854db73ee2c07d9f896aefc8 Mon Sep 17 00:00:00 2001
From: Shea Levy <shea@shealevy.com>
Date: Sun, 29 Jul 2012 01:23:51 -0400
Subject: [PATCH] Add first attempt at linux/kernel/manual-config.

The goal of this function is to make it possible to build a kernel with a user provided .config.
As a secondary goal, it will extract NixOS-relevant features from the config automatically.
As a tertiary goal, the build will aim to be simpler than the current generic kernel builder.sh.

Unfortunately, that simplicity is offset by the complexity of the feature extraction, especially since nix segfaults when trying to split the file into lines (so an import from a derivation is used)
---
 .../linux/kernel/manual-config.nix            | 81 +++++++++++++++++++
 pkgs/top-level/all-packages.nix               |  5 ++
 2 files changed, 86 insertions(+)
 create mode 100644 pkgs/os-specific/linux/kernel/manual-config.nix

diff --git a/pkgs/os-specific/linux/kernel/manual-config.nix b/pkgs/os-specific/linux/kernel/manual-config.nix
new file mode 100644
index 000000000000..8cf8b6502166
--- /dev/null
+++ b/pkgs/os-specific/linux/kernel/manual-config.nix
@@ -0,0 +1,81 @@
+{ stdenv, runCommand }:
+
+{ version, modDirVersion ? version, src, patches ? [], config }:
+
+with stdenv.lib;
+
+let
+
+  # Function to parse the config file to get the features supported
+  readFeatures = config:
+    let
+      # !!! Original causes recursion too deep, need to import from derivation
+      # linesWithComments = splitString "\n" (builtins.readFile config);
+      lines = import "${runCommand "lines.nix" {} ''
+        echo "[" >> $out
+        while read line; do
+            if [ -n "$line" ] && [ `expr index "$line" "#"` -ne 1 ]; then
+                echo "${"''"}" >> $out
+                echo $(echo $line | sed "s@${"''"}@\$\{\"${"''"}\"}@g")"${"''"}" >> $out
+            fi
+        done < ${config} 
+        echo "]" >> $out
+      ''}";
+
+      nvpairs = map (s: let split = splitString "=" s; fst = head split; in {
+        name = substring (stringLength "CONFIG_") (stringLength fst) fst;
+        value = head (tail split);
+      }) lines;
+
+      configAttrs = listToAttrs nvpairs;
+
+      getValue = option:
+        if hasAttr option configAttrs then getAttr option configAttrs else null;
+
+      isYes = option: (getValue option) == "y";
+    in
+
+    {
+      modular = isYes "MODULES";
+    };
+
+  features = readFeatures config;
+
+in
+
+stdenv.mkDerivation ({
+  name = "linux-${version}";
+
+  enableParallelBuilding = true;
+
+  passthru = {
+    inherit version modDirVersion features;
+  };
+
+  inherit patches src;
+
+  postPatch = ''
+    for mf in $(find -name Makefile); do
+        echo "stripping FHS paths in \`$mf'..."
+        sed -i "$mf" -e 's|/usr/bin/||g ; s|/bin/||g'
+    done
+  '';
+
+  configurePhase = ''
+    runHook preConfigure
+    ln -sv ${config} .config
+    make oldconfig
+    runHook postConfigure
+  '';
+
+  INSTALL_PATH = "$out";
+} // optionalAttrs features.modular {
+  MODLIB = "$out/lib/modules/${modDirVersion}";
+
+  INSTALL_MOD_STRIP = "1";
+
+  postInstall = ''
+    make modules_install $makeFlags "$\{makeFlagsArray[@]}" \
+      $installFlags "$\{installFlagsArray[@]}"
+  '';
+})
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 76918d081db0..0ca0f90768a3 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -5856,6 +5856,11 @@ let
   linux = linuxPackages.kernel;
   linuxPackages = linuxPackages_3_2;
 
+  # A function to build a manually-configured kernel
+  linuxManualConfig = import ../os-specific/linux/kernel/manual-config.nix {
+    inherit stdenv runCommand;
+  };
+
   keyutils = callPackage ../os-specific/linux/keyutils { };
 
   libselinux = callPackage ../os-specific/linux/libselinux { };