lib/systems: move kernel configuration out of the platform structure

Currently, you need to override `stdenv.hostPlatform` to request a compressed kernel on AArch64, and the kernel configuration is split between the central structured configuration and string snippets in platform definitions. This has consequently made the latter bitrot terribly. Since the platform‐specific logic is now very limited after cleaning up the detritus, we can move it into the kernel derivation and expose the relevant configuration there for anyone who wants to customize it further or needs to read it out. Co-authored-by: zowoq <59103226+zowoq@users.noreply.github.com>
2026-06-13 00:34:04 +00:00 · 2025-06-25 13:52:43 +01:00
parent a6d914805c
commit 31d1d80b3f
14 changed files with 60 additions and 150 deletions
--- a/doc/release-notes/rl-2611.section.md
+++ b/doc/release-notes/rl-2611.section.md
@@ -19,6 +19,13 @@

 - `uhttpmock` providing 0.0 ABI was removed. `uhttpmock_1_0` providing 1.0 ABI was renamed to `uhttpmock` and `uhttpmock_1_0` was kept as an alias.

+- Linux kernel configuration has been moved out of the `linux-kernel` field of the platform structure into the kernel builders:
+  - `linux-kernel.name` has been removed.
+  - `linux-kernel.target` is available as the `target` parameter and passthru attribute on the kernel builders.
+  - `linux-kernel.installTarget` has been removed, as it should not be necessary to customize.
+  - `linux-kernel.DTB` is available as the `buildDTBs` parameter and passthru attribute on the kernel builders.
+  - `linux-kernel.{autoModules,preferBuiltin,extraConfig}` were already available as kernel builder parameters.
+
 - The ARMv5 Linux kernel build now uses a standard configuration and generates a standard compressed image instead of the deprecated legacy U‐Boot image format.
  `lib.systems.{examples,platforms}.{sheevaplug,pogoplug4}` have been unified into `lib.systems.examples.armv5tel-multiplatform`.
  Note that there is no official support for ARMv5 and it is not possible to build even a simple NixOS configuration out of the box.
--- a/lib/systems/default.nix
+++ b/lib/systems/default.nix
@@ -299,12 +299,10 @@ let
        inherit
          (
            {
-              linux-kernel = args.linux-kernel or { };
              gcc = args.gcc or { };
            }
            // platforms.select final
          )
-          linux-kernel
          gcc
          ;

@@ -692,6 +690,11 @@ let
        };
      };
    in
+    # TODO: Remove in 27.05.
+    assert
+      args ? linux-kernel
+      -> throw "lib.systems.elaborate: linux-kernel has been removed; see the 26.11 release notes";
+
    assert final.useAndroidPrebuilt -> final.isAndroid;
    assert foldl' (pass: { assertion, message }: if assertion final then pass else throw message) true (
      final.parsed.abi.assertions or [ ]
--- a/lib/systems/platforms.nix
+++ b/lib/systems/platforms.nix
@@ -3,74 +3,21 @@
 # targetPlatform, etc) containing at least the minimal set of attrs
 # required (see types.parsedPlatform in lib/systems/parse.nix).  This
 # file takes an already-valid platform and further elaborates it with
-# optional fields; currently these are: linux-kernel, gcc, and rustc.
+# optional fields; currently these are: gcc, and rustc.

 { lib }:
 rec {
-  pc = {
-    linux-kernel = {
-      name = "pc";
-
-      baseConfig = "defconfig";
-      # Build whatever possible as a module, if not stated in the extra config.
-      autoModules = true;
-      target = "bzImage";
-    };
-  };
-
-  ##
-  ## POWER
-  ##
-
-  powernv = {
-    linux-kernel = {
-      name = "PowerNV";
-
-      baseConfig = "powernv_defconfig";
-      target = "vmlinux";
-      autoModules = true;
-    };
-  };
-
-  ppc64 = {
-    linux-kernel = {
-      name = "powerpc64";
-
-      baseConfig = "ppc64_defconfig";
-      target = "vmlinux";
-      autoModules = true;
-    };
-  };
-
  ##
  ## ARM
  ##

  armv5tel-multiplatform = {
-    linux-kernel = {
-      name = "armv5tel-multiplatform";
-
-      baseConfig = "multi_v5_defconfig";
-      DTB = true;
-      autoModules = true;
-      preferBuiltin = true;
-      target = "zImage";
-    };
    gcc = {
      arch = "armv5te";
    };
  };

  raspberrypi = {
-    linux-kernel = {
-      name = "raspberrypi";
-
-      baseConfig = "bcm2835_defconfig";
-      DTB = true;
-      autoModules = true;
-      preferBuiltin = true;
-      target = "zImage";
-    };
    gcc = {
      # https://en.wikipedia.org/wiki/Raspberry_Pi#Specifications
      arch = "armv6kz";
@@ -105,7 +52,6 @@ rec {

  # https://developer.android.com/ndk/guides/abis#v7a
  armv7a-android = {
-    linux-kernel.name = "armeabi-v7a";
    gcc = {
      arch = "armv7-a";
      float-abi = "softfp";
@@ -114,14 +60,6 @@ rec {
  };

  armv7l-hf-multiplatform = {
-    linux-kernel = {
-      name = "armv7l-hf-multiplatform";
-      baseConfig = "defconfig";
-      DTB = true;
-      autoModules = true;
-      preferBuiltin = true;
-      target = "zImage";
-    };
    gcc = {
      # Some table about fpu flags:
      # http://community.arm.com/servlet/JiveServlet/showImage/38-1981-3827/blogentry-103749-004812900+1365712953_thumb.png
@@ -146,14 +84,6 @@ rec {
  };

  aarch64-multiplatform = {
-    linux-kernel = {
-      name = "aarch64-multiplatform";
-      baseConfig = "defconfig";
-      DTB = true;
-      autoModules = true;
-      preferBuiltin = true;
-      target = "Image";
-    };
    gcc = {
      arch = "armv8-a";
    };
@@ -171,9 +101,6 @@ rec {
  ##

  ben_nanonote = {
-    linux-kernel = {
-      name = "ben_nanonote";
-    };
    gcc = {
      arch = "mips32";
      float = "soft";
@@ -230,17 +157,6 @@ rec {
  ## Other
  ##

-  riscv-multiplatform = {
-    linux-kernel = {
-      name = "riscv-multiplatform";
-      target = "Image";
-      autoModules = true;
-      preferBuiltin = true;
-      baseConfig = "defconfig";
-      DTB = true;
-    };
-  };
-
  loongarch64-multiplatform = {
    gcc = {
      # https://github.com/loongson/la-softdev-convention/blob/master/la-softdev-convention.adoc#10-operating-system-package-build-requirements
@@ -252,14 +168,6 @@ rec {
      # https://github.com/llvm/llvm-project/pull/132173
      cmodel = "medium";
    };
-    linux-kernel = {
-      name = "loongarch-multiplatform";
-      target = "vmlinuz.efi";
-      autoModules = true;
-      preferBuiltin = true;
-      baseConfig = "defconfig";
-      DTB = true;
-    };
  };

  # This function takes a minimally-valid "platform" and returns an
@@ -267,17 +175,13 @@ rec {
  # included in the platform in order to further elaborate it.
  select =
    platform:
-    # x86
-    if platform.isx86 then
-      pc
-
    # ARM
-    else if platform.isAarch32 then
+    if platform.isAarch32 then
      let
        version = platform.parsed.cpu.version or null;
      in
      if version == null then
-        pc
+        { }
      else if lib.versionOlder version "6" then
        armv5tel-multiplatform
      else if lib.versionOlder version "7" then
@@ -291,24 +195,9 @@ rec {
    else if platform.isLoongArch64 then
      loongarch64-multiplatform

-    else if platform.isRiscV then
-      riscv-multiplatform
-
    else if platform.parsed.cpu == lib.systems.parse.cpuTypes.mipsel then
      (import ./examples.nix { inherit lib; }).mipsel-linux-gnu

-    else if platform.isPower64 then
-      if platform.isLittleEndian then powernv else ppc64
-
-    else if platform.isSh4 then
-      {
-        linux-kernel = {
-          target = "vmlinux";
-          # SH arch doesn't have a 'make install' target.
-          installTarget = "vmlinux";
-        };
-      }
-
    else
      { };
 }
--- a/nixos/modules/hardware/device-tree.nix
+++ b/nixos/modules/hardware/device-tree.nix
@@ -123,7 +123,8 @@ in
  options = {
    hardware.deviceTree = {
      enable = lib.mkOption {
-        default = pkgs.stdenv.hostPlatform.linux-kernel.DTB or false;
+        default = config.boot.kernelPackages.kernel.buildDTBs;
+        defaultText = lib.literalExpression "config.boot.kernelPackages.kernel.buildDTBs";
        type = lib.types.bool;
        description = ''
          Build device tree files. These are used to describe the
--- a/nixos/modules/installer/netboot/netboot.nix
+++ b/nixos/modules/installer/netboot/netboot.nix
@@ -111,7 +111,7 @@ with lib;
      #!ipxe
      # Use the cmdline variable to allow the user to specify custom kernel params
      # when chainloading this script from other iPXE scripts like netboot.xyz
-      kernel ${pkgs.stdenv.hostPlatform.linux-kernel.target} init=${config.system.build.toplevel}/init initrd=initrd ${toString config.boot.kernelParams} ''${cmdline}
+      kernel ${config.boot.kernelPackages.kernel.target} init=${config.system.build.toplevel}/init initrd=initrd ${toString config.boot.kernelParams} ''${cmdline}
      initrd initrd
      boot
    '';
--- a/nixos/modules/system/activation/top-level.nix
+++ b/nixos/modules/system/activation/top-level.nix
@@ -139,8 +139,8 @@ in

    system.boot.loader.kernelFile = mkOption {
      internal = true;
-      default = pkgs.stdenv.hostPlatform.linux-kernel.target;
-      defaultText = literalExpression "pkgs.stdenv.hostPlatform.linux-kernel.target";
+      default = config.boot.kernelPackages.kernel.target;
+      defaultText = literalExpression "config.boot.kernelPackages.kernel.target";
      type = types.str;
      description = ''
        Name of the kernel file to be passed to the bootloader.
--- a/nixos/modules/system/boot/loader/generations-dir/generations-dir.nix
+++ b/nixos/modules/system/boot/loader/generations-dir/generations-dir.nix
@@ -66,7 +66,6 @@ in

    system.build.installBootLoader = generationsDirBuilder;
    system.boot.loader.id = "generationsDir";
-    system.boot.loader.kernelFile = pkgs.stdenv.hostPlatform.linux-kernel.target;

  };
 }
--- a/nixos/release.nix
+++ b/nixos/release.nix
@@ -152,7 +152,7 @@ let
    tarball
    // {
      meta = {
-        description = "NixOS system tarball for ${system} - ${stdenv.hostPlatform.linux-kernel.name}";
+        description = "NixOS system tarball for ${system}";
        maintainers = map (x: lib.maintainers.${x}) maintainers;
      };
      inherit config;
@@ -188,7 +188,7 @@ let
        modules = makeModules module { };
      };
      build = configEvaled.config.system.build;
-      kernelTarget = configEvaled.pkgs.stdenv.hostPlatform.linux-kernel.target;
+      kernelTarget = build.kernel.target;
    in
    configEvaled.pkgs.symlinkJoin {
      name = "netboot";
--- a/pkgs/build-support/vm/default.nix
+++ b/pkgs/build-support/vm/default.nix
@@ -27,11 +27,10 @@

  # ----------------------------
  # The following  arguments form the "interface" of `pkgs.vmTools`.
-  # Note that `img` is a real package, but is set to this default in `all-packages.nix`.
  # ----------------------------
  customQemu ? null,
  kernel ? linux,
-  img ? stdenv.hostPlatform.linux-kernel.target,
+  img ? kernel.target,
  storeDir ? builtins.storeDir,
  rootModules ? [
    "virtio_pci"
--- a/pkgs/os-specific/linux/kernel/build.nix
+++ b/pkgs/os-specific/linux/kernel/build.nix
@@ -63,6 +63,19 @@ lib.makeOverridable (
    kernelPatches ? [ ],
    # The kernel .config file
    configfile,
+    target ?
+      if stdenv.hostPlatform.isx86 then
+        "bzImage"
+      else if stdenv.hostPlatform.isAarch32 then
+        "zImage"
+      else if stdenv.hostPlatform.isAarch64 || stdenv.hostPlatform.isRiscV then
+        "Image"
+      else if stdenv.hostPlatform.isLoongArch64 then
+        "vmlinuz.efi"
+      else
+        "vmlinux",
+    buildDTBs ?
+      stdenv.hostPlatform.isAarch || stdenv.hostPlatform.isRiscV || stdenv.hostPlatform.isLoongArch64,
    # Manually specified nixexpr representing the config
    # If unspecified, this will be autodetected from the .config
    config ? lib.optionalAttrs (builtins.isPath configfile || allowImportFromDerivation) (
@@ -139,9 +152,7 @@ lib.makeOverridable (
    isModular = config.isYes "MODULES";
    withRust = config.isYes "RUST";

-    target = stdenv.hostPlatform.linux-kernel.target or "vmlinux";
-
-    buildDTBs = stdenv.hostPlatform.linux-kernel.DTB or false;
+    inherit buildDTBs target;

    # Dependencies that are required to build kernel modules
    moduleBuildDependencies = [
@@ -204,7 +215,7 @@ lib.makeOverridable (

    buildFlags = [
      "KBUILD_BUILD_VERSION=1-NixOS"
-      stdenv.hostPlatform.linux-kernel.target
+      target
      "vmlinux" # for "perf" and things like that
      "scripts_gdb"
    ]
@@ -496,6 +507,8 @@ lib.makeOverridable (
        config
        kernelPatches
        configfile
+        target
+        buildDTBs
        moduleBuildDependencies
        stdenv
        commonMakeFlags
@@ -511,7 +524,7 @@ lib.makeOverridable (

    # Some image types need special install targets
    installTargets = [
-      (stdenv.hostPlatform.linux-kernel.installTarget or (
+      (
        if
          (target == "zImage" || target == "Image.gz" || target == "vmlinuz.efi")
          && builtins.elem stdenv.hostPlatform.linuxArch [
@@ -525,7 +538,6 @@ lib.makeOverridable (
        else
          "install"
      )
-      )
    ];

    karch = stdenv.hostPlatform.linuxArch;
--- a/pkgs/os-specific/linux/kernel/common-config.nix
+++ b/pkgs/os-specific/linux/kernel/common-config.nix
@@ -1130,7 +1130,7 @@ let
        useZstd = stdenv.buildPlatform.is64bit;
      in
      {
-        # stdenv.hostPlatform.linux-kernel.target assumes uncompressed on RISC-V.
+        # The default target assumes uncompressed on RISC-V.
        KERNEL_UNCOMPRESSED = lib.mkIf stdenv.hostPlatform.isRiscV yes;

        KERNEL_XZ = lib.mkIf (
--- a/pkgs/os-specific/linux/kernel/common-flags.nix
+++ b/pkgs/os-specific/linux/kernel/common-flags.nix
@@ -36,5 +36,4 @@
    "CFLAGS_KERNEL=-I${clangLib}/lib/clang/${majorVer}/include"
  ]
 )
-++ (stdenv.hostPlatform.linux-kernel.makeFlags or [ ])
 ++ extraMakeFlags
--- a/pkgs/os-specific/linux/kernel/generic.nix
+++ b/pkgs/os-specific/linux/kernel/generic.nix
@@ -32,7 +32,16 @@ lib.makeOverridable (
    version,

    # Allows overriding the default defconfig
-    defconfig ? null,
+    # TODO: Reconsider some of these defaults?
+    defconfig ?
+      if stdenv.hostPlatform.isAarch32 && stdenv.hostPlatform.parsed.cpu.version or null == "5" then
+        "multi_v5_defconfig"
+      else if stdenv.hostPlatform.isAarch32 && stdenv.hostPlatform.parsed.cpu.version or null == "6" then
+        "bcm2835_defconfig"
+      else if stdenv.hostPlatform.isPower64 then
+        if stdenv.hostPlatform.isLittleEndian then "powernv_defconfig" else "ppc64_defconfig"
+      else
+        "defconfig",

    # Legacy overrides to the intermediate kernel config, as string
    extraConfig ? "",
@@ -66,20 +75,17 @@ lib.makeOverridable (
    # symbolic name and `patch' is the actual patch.  The patch may
    # optionally be compressed with gzip or bzip2.
    kernelPatches ? [ ],
-    ignoreConfigErrors ?
-      !lib.elem stdenv.hostPlatform.linux-kernel.name or "" [
-        "aarch64-multiplatform"
-        "pc"
-      ],
+    ignoreConfigErrors ? !(stdenv.hostPlatform.isx86 || stdenv.hostPlatform.isAarch64),
    extraMeta ? { },
    extraPassthru ? { },

    isLTS ? false,
    isZen ? false,

-    # easy overrides to stdenv.hostPlatform.linux-kernel members
-    autoModules ? stdenv.hostPlatform.linux-kernel.autoModules or true,
-    preferBuiltin ? stdenv.hostPlatform.linux-kernel.preferBuiltin or false,
+    autoModules ? true,
+    # TODO: Remove this default?
+    preferBuiltin ?
+      stdenv.hostPlatform.isAarch || stdenv.hostPlatform.isRiscV || stdenv.hostPlatform.isLoongArch64,
    kernelArch ? stdenv.hostPlatform.linuxArch,
    kernelTests ? { },

@@ -116,9 +122,7 @@ lib.makeOverridable (
    intermediateNixConfig =
      configfile.moduleStructuredConfig.intermediateNixConfig
      # extra config in legacy string format
-      + extraConfig
-      # need the 'or ""' at the end in case enableCommonConfig = true and extraConfig is not present
-      + lib.optionalString enableCommonConfig stdenv.hostPlatform.linux-kernel.extraConfig or "";
+      + extraConfig;

    structuredConfigFromPatches = map (
      {
@@ -205,8 +209,7 @@ lib.makeOverridable (
      buildPhase =
        let
          # e.g. "defconfig"
-          kernelBaseConfig =
-            if defconfig != null then defconfig else stdenv.hostPlatform.linux-kernel.baseConfig or "defconfig";
+          kernelBaseConfig = defconfig;
          kernelIntermediateConfig = writeText "kernel-intermediate-config" (
            kernelConfigFun intermediateNixConfig
          );
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -909,9 +909,7 @@ with pkgs;
    inherit (darwin) signingUtils;
  };

-  vmTools = callPackage ../build-support/vm {
-    img = stdenv.hostPlatform.linux-kernel.target;
-  };
+  vmTools = callPackage ../build-support/vm { };

  releaseTools = callPackage ../build-support/release { };