set gcc.arch, extra-platforms, system-features

[zowoq]

?

diff --git a/nixos/modules/config/nix.nix b/nixos/modules/config/nix.nix
index 9505c60d4f63..7b437f6f88f0 100644
--- a/nixos/modules/config/nix.nix
+++ b/nixos/modules/config/nix.nix
@@ -379,10 +379,10 @@ in
       substituters = mkAfter [ "https://cache.nixos.org/" ];
       system-features = mkDefault (
         [ "nixos-test" "benchmark" "big-parallel" "kvm" ] ++
-        optionals (pkgs.stdenv.hostPlatform ? gcc.arch) (
+        optionals (config.nixpkgs.hostPlatform ? gcc.arch) (
           # a builder can run code for `gcc.arch` and inferior architectures
-          [ "gccarch-${pkgs.stdenv.hostPlatform.gcc.arch}" ] ++
-          map (x: "gccarch-${x}") (systems.architectures.inferiors.${pkgs.stdenv.hostPlatform.gcc.arch} or [])
+          [ "gccarch-${config.nixpkgs.hostPlatform.gcc.arch}" ] ++
+          map (x: "gccarch-${x}") (systems.architectures.inferiors.${config.nixpkgs.hostPlatform.gcc.arch} or [])
         )
       );
     };