buildLinux: apply hostPlatform.linux-kernel.makeFlags to generate-config.pl

This enforces that the configuration generated will obey any/all flags
set in the platform/stdenv configuration. This is crucial, for example,
if you'd like to build a kernel using clang.

Without this patch, anything you set in
`stdenv.hostPlatform.linux-kernel.makeFlags` is wholly ignored during
config generation, causing (for example) any changes in the desired
toolchain (e.g. `LLVM`, `LLVM_IAS`) to not be reflected in the generated
config, and for the subsequent build to fail.

1 files changed, 6 insertions, 2 deletions

diff --git a/pkgs/os-specific/linux/kernel/generic.nix b/pkgs/os-specific/linux/kernel/generic.nix
index b35c84513e69e..f208da7f30ec7 100644
--- a/pkgs/os-specific/linux/kernel/generic.nix
+++ b/pkgs/os-specific/linux/kernel/generic.nix
@@ -116,6 +116,8 @@ let
     # e.g. "bzImage"
     kernelTarget = stdenv.hostPlatform.linux-kernel.target;
 
+    makeFlags = lib.optionals (stdenv.hostPlatform.linux-kernel ? makeFlags) stdenv.hostPlatform.linux-kernel.makeFlags;
+
     prePatch = kernel.prePatch + ''
       # Patch kconfig to print "###" after every question so that
       # generate-config.pl from the generic builder can answer them.
@@ -137,13 +139,15 @@ let
       make -C . O="$buildRoot" $kernelBaseConfig \
           ARCH=$kernelArch \
           HOSTCC=$HOSTCC HOSTCXX=$HOSTCXX HOSTAR=$HOSTAR HOSTLD=$HOSTLD \
-          CC=$CC OBJCOPY=$OBJCOPY OBJDUMP=$OBJDUMP READELF=$READELF
+          CC=$CC OBJCOPY=$OBJCOPY OBJDUMP=$OBJDUMP READELF=$READELF \
+          $makeFlags
 
       # Create the config file.
       echo "generating kernel configuration..."
       ln -s "$kernelConfigPath" "$buildRoot/kernel-config"
       DEBUG=1 ARCH=$kernelArch KERNEL_CONFIG="$buildRoot/kernel-config" AUTO_MODULES=$autoModules \
-           PREFER_BUILTIN=$preferBuiltin BUILD_ROOT="$buildRoot" SRC=. perl -w $generateConfig
+        PREFER_BUILTIN=$preferBuiltin BUILD_ROOT="$buildRoot" SRC=. MAKE_FLAGS="$makeFlags" \
+        perl -w $generateConfig
     '';
 
     installPhase = "mv $buildRoot/.config $out";