From 3dccb26e6cc04dd89983f2914ec67bb68733cc93 Mon Sep 17 00:00:00 2001
From: Franz Pletz <fpletz@fnordicwalking.de>
Date: Wed, 3 Jul 2024 23:31:38 +0200
Subject: [PATCH] linux: multiple outputs for kernel targets

This adds outputs for all built kernel targets and provides symlinks to
all built images in the default output for compatibility. This way we
can get rid of `lib.platforms.*.linux-kernel.target` eventually and we
don't have to build the kernel multiple times for every target.
---
 pkgs/os-specific/linux/kernel/generic.nix     | 17 +++++++++-
 .../linux/kernel/manual-config.nix            | 34 ++++++++++++-------
 2 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/pkgs/os-specific/linux/kernel/generic.nix b/pkgs/os-specific/linux/kernel/generic.nix
index 5981de6732426..cdad5d1638bfd 100644
--- a/pkgs/os-specific/linux/kernel/generic.nix
+++ b/pkgs/os-specific/linux/kernel/generic.nix
@@ -1,3 +1,12 @@
+let
+  # Map of images representations to legacy Makefile targets.
+  defaultMapKernelToInstallTargets = {
+    "uImage" = "uinstall";
+    "zImage" = "zinstall";
+    "Image.gz" = "zinstall";
+    "vmlinuz.efi" = "zinstall";
+  };
+in
 { buildPackages
 , callPackage
 , perl
@@ -70,6 +79,12 @@ lib.makeOverridable ({ # The kernel source tarball.
 # easy overrides to stdenv.hostPlatform.linux-kernel members
 , autoModules ? stdenv.hostPlatform.linux-kernel.autoModules
 , preferBuiltin ? stdenv.hostPlatform.linux-kernel.preferBuiltin or false
+, kernelTargets ?
+    if stdenv.hostPlatform.isAarch64 then
+      ["Image" "vmlinuz.efi"]
+    else
+      [stdenv.hostPlatform.linux-kernel.target]
+, installTargets ? lib.unique (map (target: defaultMapKernelToInstallTargets.${target} or "install") kernelTargets)
 , kernelArch ? stdenv.hostPlatform.linuxArch
 , kernelTests ? []
 
@@ -214,7 +229,7 @@ let
   }; # end of configfile derivation
 
   kernel = (callPackage ./manual-config.nix { inherit lib stdenv buildPackages; }) (basicArgs // {
-    inherit kernelPatches randstructSeed extraMakeFlags extraMeta configfile modDirVersion;
+    inherit kernelPatches randstructSeed extraMakeFlags extraMeta configfile modDirVersion kernelTargets installTargets;
     pos = builtins.unsafeGetAttrPos "version" args;
 
     config = {
diff --git a/pkgs/os-specific/linux/kernel/manual-config.nix b/pkgs/os-specific/linux/kernel/manual-config.nix
index 9c30f1fd70d08..b8bbbdbbd8cad 100644
--- a/pkgs/os-specific/linux/kernel/manual-config.nix
+++ b/pkgs/os-specific/linux/kernel/manual-config.nix
@@ -33,6 +33,13 @@ in lib.makeOverridable ({
   src,
   # a list of { name=..., patch=..., extraConfig=...} patches
   kernelPatches ? [],
+  # kernel image build targets like Image, bzImage, Image.gz, vmlinuz.efi
+  kernelTargets ? [],
+  # a list of install targets, e.g. :
+  # - uinstall for uImage, U-Boot wrapped image
+  # - zinstall for zImage, self-extracting images
+  # - install, the generic binary image
+  installTargets ? [],
   # The kernel .config file
   configfile,
   # Manually specified nixexpr representing the config
@@ -64,7 +71,9 @@ let
   # Shadow the un-defaulted parameter; don't want null.
   modDirVersion = modDirVersion_;
   inherit (lib)
-    hasAttr getAttr optional optionals optionalString optionalAttrs maintainers platforms;
+    hasAttr getAttr optional optionals optionalString optionalAttrs genAttrs replaceStrings maintainers platforms;
+
+  targetsToOutput = genAttrs kernelTargets (target: replaceStrings ["."] ["-"] target);
 
   drvAttrs = config_: kernelConf: kernelPatches: configfile:
     let
@@ -128,10 +137,10 @@ let
       ++ optionals withRust [ rustc rust-bindgen ]
       ;
 
-    in (optionalAttrs isModular { outputs = [ "out" "dev" ]; }) // {
+    in (optionalAttrs isModular { outputs = [ "out" "dev" ] ++ (lib.attrValues targetsToOutput); }) // {
       passthru = rec {
         inherit version modDirVersion config kernelPatches configfile
-          moduleBuildDependencies stdenv;
+          moduleBuildDependencies stdenv targetsToOutput;
         inherit isZen isHardened isLibre withRust;
         isXen = lib.warn "The isXen attribute is deprecated. All Nixpkgs kernels that support it now have Xen enabled." true;
         baseVersion = lib.head (lib.splitString "-rc" version);
@@ -242,7 +251,7 @@ let
 
       buildFlags = [
         "KBUILD_BUILD_VERSION=1-NixOS"
-        kernelConf.target
+      ] ++ kernelTargets ++ [
         "vmlinux"  # for "perf" and things like that
       ] ++ optional isModular "modules"
         ++ optionals buildDTBs ["dtbs" "DTC_FLAGS=-@"]
@@ -309,15 +318,14 @@ let
         export HOME=${installkernel}
       '';
 
-      # Some image types need special install targets (e.g. uImage is installed with make uinstall on arm)
-      installTargets = [
-        (kernelConf.installTarget or (
-          /**/ if kernelConf.target == "uImage" && stdenv.hostPlatform.linuxArch == "arm" then "uinstall"
-          else if kernelConf.target == "zImage" || kernelConf.target == "Image.gz" || kernelConf.target == "vmlinuz.efi" then "zinstall"
-          else "install"))
-      ];
+      # Some image types need special install targets (e.g. uImage is installed with make uinstall)
+      installTargets = if installTargets == [ ] then [ "install" ] else installTargets;
 
-      postInstall = optionalString isModular ''
+      postInstall = (lib.concatStringsSep "\n" (lib.mapAttrsToList (target: output: ''
+        mkdir -p "''${${output}}"
+        moveToOutput "${target}" "''${${output}}"
+        ln -sf "''${${output}}/${target}" "$out/${target}"
+      '') targetsToOutput)) + (optionalString isModular ''
         mkdir -p $dev
         cp vmlinux $dev/
         if [ -z "''${dontStrip-}" ]; then
@@ -387,7 +395,7 @@ let
 
         # Delete empty directories
         find -empty -type d -delete
-      '';
+      '');
 
       requiredSystemFeatures = [ "big-parallel" ];