lib: Clean up how linux and gcc config is specified

The `platform` field is pointless nesting: it's just stuff that happens
to be defined together, and that should be an implementation detail.

This instead makes `linux-kernel` and `gcc` top level fields in platform
configs. They join `rustc` there [all are optional], which was put there
and not in `platform` in anticipation of a change like this.

`linux-kernel.arch` in particular also becomes `linuxArch`, to match the
other `*Arch`es.

The next step after is this to combine the *specific* machines from
`lib.systems.platforms` with `lib.systems.examples`, keeping just the
"multiplatform" ones for defaulting.

8 files changed, 30 insertions, 14 deletions

diff --git a/nixos/doc/manual/release-notes/rl-2103.xml b/nixos/doc/manual/release-notes/rl-2103.xml
index e46d1ca403f3..408c896defee 100644
--- a/nixos/doc/manual/release-notes/rl-2103.xml
+++ b/nixos/doc/manual/release-notes/rl-2103.xml
@@ -592,6 +592,22 @@ http://some.json-exporter.host:7979/probe?target=https://example.com/some/json/e
      <literal>/etc/netgroup</literal> defines network-wide groups and may affect to setups using NIS.
     </para>
    </listitem>
+   <listitem>
+    <para>
+     Platforms, like <varname>stdenv.hostPlatform</varname>, no longer have a <varname>platform</varname> attribute.
+     It has been (mostly) flattoned away:
+    </para>
+    <itemizedlist>
+     <listitem><para><varname>platform.gcc</varname> is now <varname>gcc</varname></para></listitem>
+     <listitem><para><literal>platform.kernel*</literal> is now <literal>linux-kernel.*</literal></para></listitem>
+    </itemizedlist>
+    <para>
+     Additionally, <varname>platform.kernelArch</varname> moved to the top level as <varname>linuxArch</varname> to match the other <literal>*Arch</literal> variables.
+    </para>
+    <para>
+     The <varname>platform</varname> grouping of these things never meant anything, and was just a historial/implementation artifact that was overdue removal.
+    </para>
+   </listitem>
   </itemizedlist>
  </section>
 </section>
diff --git a/nixos/modules/hardware/device-tree.nix b/nixos/modules/hardware/device-tree.nix
index e0ab37bca63a..4aa1d6369d1b 100644
--- a/nixos/modules/hardware/device-tree.nix
+++ b/nixos/modules/hardware/device-tree.nix
@@ -68,11 +68,11 @@ let
       patchShebangs scripts/*
       substituteInPlace scripts/Makefile.lib \
         --replace 'DTC_FLAGS += $(DTC_FLAGS_$(basetarget))' 'DTC_FLAGS += $(DTC_FLAGS_$(basetarget)) -@'
-      make ${pkgs.stdenv.hostPlatform.platform.kernelBaseConfig} ARCH="${pkgs.stdenv.hostPlatform.platform.kernelArch}"
-      make dtbs ARCH="${pkgs.stdenv.hostPlatform.platform.kernelArch}"
+      make ${pkgs.stdenv.hostPlatform.linux-kernel.baseConfig} ARCH="${pkgs.stdenv.hostPlatform.linuxArch}"
+      make dtbs ARCH="${pkgs.stdenv.hostPlatform.linuxArch}"
     '';
     installPhase = ''
-      make dtbs_install INSTALL_DTBS_PATH=$out/dtbs  ARCH="${pkgs.stdenv.hostPlatform.platform.kernelArch}"
+      make dtbs_install INSTALL_DTBS_PATH=$out/dtbs  ARCH="${pkgs.stdenv.hostPlatform.linuxArch}"
     '';
   };
 
@@ -115,7 +115,7 @@ in
   options = {
       hardware.deviceTree = {
         enable = mkOption {
-          default = pkgs.stdenv.hostPlatform.platform.kernelDTB or false;
+          default = pkgs.stdenv.hostPlatform.linux-kernel.DTB or false;
           type = types.bool;
           description = ''
             Build device tree files. These are used to describe the
diff --git a/nixos/modules/installer/netboot/netboot.nix b/nixos/modules/installer/netboot/netboot.nix
index 95eba86bcb65..fa074fdfcc6e 100644
--- a/nixos/modules/installer/netboot/netboot.nix
+++ b/nixos/modules/installer/netboot/netboot.nix
@@ -88,7 +88,7 @@ with lib;
 
     system.build.netbootIpxeScript = pkgs.writeTextDir "netboot.ipxe" ''
       #!ipxe
-      kernel ${pkgs.stdenv.hostPlatform.platform.kernelTarget} init=${config.system.build.toplevel}/init initrd=initrd ${toString config.boot.kernelParams}
+      kernel ${pkgs.stdenv.hostPlatform.linux-kernel.target} init=${config.system.build.toplevel}/init initrd=initrd ${toString config.boot.kernelParams}
       initrd initrd
       boot
     '';
diff --git a/nixos/modules/services/misc/nix-daemon.nix b/nixos/modules/services/misc/nix-daemon.nix
index 0eeff31d6c4d..64bdbf159d51 100644
--- a/nixos/modules/services/misc/nix-daemon.nix
+++ b/nixos/modules/services/misc/nix-daemon.nix
@@ -587,10 +587,10 @@ in
 
     nix.systemFeatures = mkDefault (
       [ "nixos-test" "benchmark" "big-parallel" "kvm" ] ++
-      optionals (pkgs.hostPlatform.platform ? gcc.arch) (
-        # a builder can run code for `platform.gcc.arch` and inferior architectures
-        [ "gccarch-${pkgs.hostPlatform.platform.gcc.arch}" ] ++
-        map (x: "gccarch-${x}") lib.systems.architectures.inferiors.${pkgs.hostPlatform.platform.gcc.arch}
+      optionals (pkgs.hostPlatform ? gcc.arch) (
+        # a builder can run code for `gcc.arch` and inferior architectures
+        [ "gccarch-${pkgs.hostPlatform.gcc.arch}" ] ++
+        map (x: "gccarch-${x}") lib.systems.architectures.inferiors.${pkgs.hostPlatform.gcc.arch}
       )
     );
 
diff --git a/nixos/modules/system/activation/top-level.nix b/nixos/modules/system/activation/top-level.nix
index 03d7e7493230..b0f77ca3fb8d 100644
--- a/nixos/modules/system/activation/top-level.nix
+++ b/nixos/modules/system/activation/top-level.nix
@@ -190,7 +190,7 @@ in
 
     system.boot.loader.kernelFile = mkOption {
       internal = true;
-      default = pkgs.stdenv.hostPlatform.platform.kernelTarget;
+      default = pkgs.stdenv.hostPlatform.linux-kernel.target;
       type = types.str;
       description = ''
         Name of the kernel file to be passed to the bootloader.
diff --git a/nixos/modules/system/boot/loader/generations-dir/generations-dir.nix b/nixos/modules/system/boot/loader/generations-dir/generations-dir.nix
index 2d27611946e2..fee567a510ba 100644
--- a/nixos/modules/system/boot/loader/generations-dir/generations-dir.nix
+++ b/nixos/modules/system/boot/loader/generations-dir/generations-dir.nix
@@ -59,7 +59,7 @@ in
 
     system.build.installBootLoader = generationsDirBuilder;
     system.boot.loader.id = "generationsDir";
-    system.boot.loader.kernelFile = platform.kernelTarget;
+    system.boot.loader.kernelFile = linux-kernel.target;
 
   };
 }
diff --git a/nixos/modules/system/boot/loader/raspberrypi/raspberrypi.nix b/nixos/modules/system/boot/loader/raspberrypi/raspberrypi.nix
index ba936b265732..db22dd36cbea 100644
--- a/nixos/modules/system/boot/loader/raspberrypi/raspberrypi.nix
+++ b/nixos/modules/system/boot/loader/raspberrypi/raspberrypi.nix
@@ -103,6 +103,6 @@ in
 
     system.build.installBootLoader = builder;
     system.boot.loader.id = "raspberrypi";
-    system.boot.loader.kernelFile = platform.kernelTarget;
+    system.boot.loader.kernelFile = linux-kernel.target;
   };
 }
diff --git a/nixos/release.nix b/nixos/release.nix
index 1f5c15812695..109747945f78 100644
--- a/nixos/release.nix
+++ b/nixos/release.nix
@@ -79,7 +79,7 @@ let
     in
       tarball //
         { meta = {
-            description = "NixOS system tarball for ${system} - ${stdenv.hostPlatform.platform.name}";
+            description = "NixOS system tarball for ${system} - ${stdenv.hostPlatform.linux-kernel.name}";
             maintainers = map (x: lib.maintainers.${x}) maintainers;
           };
           inherit config;
@@ -105,7 +105,7 @@ let
         modules = makeModules module {};
       };
       build = configEvaled.config.system.build;
-      kernelTarget = configEvaled.pkgs.stdenv.hostPlatform.platform.kernelTarget;
+      kernelTarget = configEvaled.pkgs.stdenv.hostPlatform.linux-kernel.target;
     in
       pkgs.symlinkJoin {
         name = "netboot";