From ea167e8ccbcae6a3378e622255d9705d26f33058 Mon Sep 17 00:00:00 2001
From: Bernardo Meurer <bernardo@meurer.org>
Date: Sun, 11 Jul 2021 21:58:16 -0700
Subject: [PATCH] buildLinux: take and propagate extraMakeFlags

This is just for practicity, as it allows users of buildLinux to pass
along extra flags they need in the kernel's make invocation. This makes,
for example, supporting LLVM _much_ easier, and could enable us in the
future to provide clang-built kernels.
---
 pkgs/os-specific/linux/kernel/generic.nix       | 13 +++++++++----
 pkgs/os-specific/linux/kernel/manual-config.nix |  8 ++++++--
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/pkgs/os-specific/linux/kernel/generic.nix b/pkgs/os-specific/linux/kernel/generic.nix
index f208da7f30ec..29557b8d9e2e 100644
--- a/pkgs/os-specific/linux/kernel/generic.nix
+++ b/pkgs/os-specific/linux/kernel/generic.nix
@@ -21,6 +21,9 @@
 , # Legacy overrides to the intermediate kernel config, as string
   extraConfig ? ""
 
+  # Additional make flags passed to kbuild
+, extraMakeFlags ? []
+
 , # kernel intermediate config overrides, as a set
  structuredExtraConfig ? {}
 
@@ -97,7 +100,7 @@ let
     in lib.concatStringsSep "\n" ([baseConfigStr] ++ configFromPatches);
 
   configfile = stdenv.mkDerivation {
-    inherit ignoreConfigErrors autoModules preferBuiltin kernelArch;
+    inherit ignoreConfigErrors autoModules preferBuiltin kernelArch extraMakeFlags;
     pname = "linux-config";
     inherit version;
 
@@ -116,7 +119,8 @@ let
     # e.g. "bzImage"
     kernelTarget = stdenv.hostPlatform.linux-kernel.target;
 
-    makeFlags = lib.optionals (stdenv.hostPlatform.linux-kernel ? makeFlags) stdenv.hostPlatform.linux-kernel.makeFlags;
+    makeFlags = lib.optionals (stdenv.hostPlatform.linux-kernel ? makeFlags) stdenv.hostPlatform.linux-kernel.makeFlags
+      ++ extraMakeFlags;
 
     prePatch = kernel.prePatch + ''
       # Patch kconfig to print "###" after every question so that
@@ -136,7 +140,8 @@ let
       export HOSTLD=$LD_FOR_BUILD
 
       # Get a basic config file for later refinement with $generateConfig.
-      make -C . O="$buildRoot" $kernelBaseConfig \
+      make $makeFlags \
+          -C . O="$buildRoot" $kernelBaseConfig \
           ARCH=$kernelArch \
           HOSTCC=$HOSTCC HOSTCXX=$HOSTCXX HOSTAR=$HOSTAR HOSTLD=$HOSTLD \
           CC=$CC OBJCOPY=$OBJCOPY OBJDUMP=$OBJDUMP READELF=$READELF \
@@ -176,7 +181,7 @@ let
   }; # end of configfile derivation
 
   kernel = (callPackage ./manual-config.nix {}) {
-    inherit version modDirVersion src kernelPatches randstructSeed lib stdenv extraMeta configfile;
+    inherit version modDirVersion src kernelPatches randstructSeed lib stdenv extraMakeFlags extraMeta configfile;
 
     config = { CONFIG_MODULES = "y"; CONFIG_FW_LOADER = "m"; };
   };
diff --git a/pkgs/os-specific/linux/kernel/manual-config.nix b/pkgs/os-specific/linux/kernel/manual-config.nix
index d40a36936a26..77add0aef539 100644
--- a/pkgs/os-specific/linux/kernel/manual-config.nix
+++ b/pkgs/os-specific/linux/kernel/manual-config.nix
@@ -19,6 +19,8 @@ in {
   stdenv,
   # The kernel version
   version,
+  # Additional kernel make flags
+  extraMakeFlags ? [],
   # The version of the kernel module directory
   modDirVersion ? version,
   # The kernel source (tarball, git checkout, etc.)
@@ -173,7 +175,9 @@ let
         "KBUILD_BUILD_VERSION=1-NixOS"
         kernelConf.target
         "vmlinux"  # for "perf" and things like that
-      ] ++ optional isModular "modules";
+      ]
+      ++ optional isModular "modules"
+      ++ extraMakeFlags;
 
       installFlags = [
         "INSTALLKERNEL=${installkernel}"
@@ -325,7 +329,7 @@ stdenv.mkDerivation ((drvAttrs config stdenv.hostPlatform.linux-kernel kernelPat
     "ARCH=${stdenv.hostPlatform.linuxArch}"
   ] ++ lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) [
     "CROSS_COMPILE=${stdenv.cc.targetPrefix}"
-  ];
+  ] ++ extraMakeFlags;
 
   karch = stdenv.hostPlatform.linuxArch;
 })