linux: simplify toolchain selection

When we set CROSS_COMPILE to set the toolchain prefix, everything works out of the box without trying to drop absolute paths everywhere. This removes a lot of duplication from the kernel derivations.
NixOS · Oct 21, 2024 · 89da132 · 89da132
1 parent a2f6525
commit 89da132
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Showing 3 changed files with 10 additions and 37 deletions.
diff --git a/pkgs/os-specific/linux/kernel/generate-config.pl b/pkgs/os-specific/linux/kernel/generate-config.pl
@@ -46,8 +46,7 @@ sub runConfig {
  # required to get clang LTO working, among other things.
  my $pid = open2(\*IN, \*OUT,
  "make -C $ENV{SRC} O=$buildRoot config"
- . " SHELL=bash ARCH=$ENV{ARCH} CC=$ENV{CC} HOSTCC=$ENV{HOSTCC} HOSTCXX=$ENV{HOSTCXX}"
- . " LD=$ENV{LD} NM=$ENV{NM} AR=$ENV{AR} OBJCOPY=$ENV{OBJCOPY}"
+ . " SHELL=bash ARCH=$ENV{ARCH} CROSS_COMPILE=$ENV{CROSS_COMPILE}"
  . " $makeFlags");
 
  # Parse the output, look for questions and then send an

diff --git a/pkgs/os-specific/linux/kernel/generic.nix b/pkgs/os-specific/linux/kernel/generic.nix
@@ -166,34 +166,18 @@ let
 
  buildPhase = ''
  export buildRoot="''${buildRoot:-build}"
- export HOSTCC=$CC_FOR_BUILD
- export HOSTCXX=$CXX_FOR_BUILD
- export HOSTAR=$AR_FOR_BUILD
- export HOSTLD=$LD_FOR_BUILD
-
- # Absolute paths for tools avoid any PATH-clobbering issues.
- export CC=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}cc
- export LD=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}ld
- export AR=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}ar
- export NM=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}nm
- export STRIP=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}strip
- export OBJCOPY=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}objcopy
- export OBJDUMP=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}objdump
- export READELF=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}readelf
 
  # Get a basic config file for later refinement with $generateConfig.
  make $makeFlags \
  -C . O="$buildRoot" $kernelBaseConfig \
- ARCH=$kernelArch \
- HOSTCC=$HOSTCC HOSTCXX=$HOSTCXX HOSTAR=$HOSTAR HOSTLD=$HOSTLD \
- CC=$CC OBJCOPY=$OBJCOPY OBJDUMP=$OBJDUMP READELF=$READELF \
- LD=$LD AR=$AR NM=$NM STRIP=$STRIP \
+ ARCH=$kernelArch CROSS_COMPILE=${stdenv.cc.targetPrefix} \
  $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=$autoModules \
+ DEBUG=1 ARCH=$kernelArch CROSS_COMPILE=${stdenv.cc.targetPrefix} \
+ KERNEL_CONFIG="$buildRoot/kernel-config" AUTO_MODULES=$autoModules \
  PREFER_BUILTIN=$preferBuiltin BUILD_ROOT="$buildRoot" SRC=. MAKE_FLAGS="$makeFlags" \
  perl -w $generateConfig
  '';

diff --git a/pkgs/os-specific/linux/kernel/manual-config.nix b/pkgs/os-specific/linux/kernel/manual-config.nix
@@ -426,24 +426,14 @@ stdenv.mkDerivation ((drvAttrs config stdenv.hostPlatform.linux-kernel kernelPat
  # Absolute paths for compilers avoid any PATH-clobbering issues.
  makeFlags = [
  "O=$(buildRoot)"
- "CC=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}cc"
- "LD=${if stdenv.isx86_64 && stdenv.cc.bintools.isLLVM
- then
- # The wrapper for ld.lld breaks linking the kernel. We use the unwrapped linker as workaround. See:
- # https://github.com/NixOS/nixpkgs/issues/321667
- stdenv.cc.bintools.bintools
- else stdenv.cc}/bin/${stdenv.cc.targetPrefix}ld"
- "AR=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}ar"
- "NM=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}nm"
- "STRIP=${stdenv.cc.bintools.bintools}/bin/${stdenv.cc.targetPrefix}strip"
- "OBJCOPY=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}objcopy"
- "OBJDUMP=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}objdump"
- "READELF=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}readelf"
- "HOSTCC=${buildPackages.stdenv.cc}/bin/${buildPackages.stdenv.cc.targetPrefix}cc"
- "HOSTLD=${buildPackages.stdenv.cc.bintools}/bin/${buildPackages.stdenv.cc.targetPrefix}ld"
  "ARCH=${stdenv.hostPlatform.linuxArch}"
- ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
  "CROSS_COMPILE=${stdenv.cc.targetPrefix}"
+ ] ++ lib.optionals (stdenv.isx86_64 && stdenv.cc.bintools.isLLVM) [
+ # The wrapper for ld.lld breaks linking the kernel. We use the
+ # unwrapped linker as workaround. See:
+ #
+ # https://github.com/NixOS/nixpkgs/issues/321667
+ "LD=${stdenv.cc.bintools.bintools}/bin/${stdenv.cc.targetPrefix}ld"
  ] ++ (stdenv.hostPlatform.linux-kernel.makeFlags or [])
  ++ extraMakeFlags;