Adds mobile.system.platform

devices/asus-z00t/default.nix

@@ -18,6 +18,8 @@
       fb_modes = ./fb.modes;
     };
   };
+
+  mobile.system.platform = "aarch64-linux";
   mobile.system.type = "android-bootimg";
   mobile.boot.stage-1 = {
     extraUtils = with pkgs; [

devices/qemu-x86_64/default.nix

@@ -60,6 +60,8 @@ in
     };
     ram = 512;
   };
+
+  mobile.system.platform = "x86_64-linux";
   mobile.system.type = "kernel-initrd";
   mobile.boot.stage-1 = {
     redirect-log.targets = lib.mkIf (splash != true) [ "/dev/tty0" ];

modules/module-list.nix

@@ -29,5 +29,6 @@ in
   ./nixpkgs.nix
   ./quirks-qualcomm.nix
   ./system-build.nix
+  ./system-target.nix
   ./system-types.nix
 ]

modules/system-target.nix

@@ -0,0 +1,36 @@
+{ config, lib, pkgs, ... }:
+
+# FIXME : current implementation only works for native x86_64 built hosts.
+
+with lib;
+let
+  cfg = config.mobile.system;
+
+  target_types = {
+    aarch64-linux = lib.systems.examples.aarch64-multiplatform;
+    x86_64-linux = null; # TODO : cross-compile from ARM and others!
+  };
+in
+{
+  options.mobile = {
+    system.platform = mkOption {
+      type = types.enum (lib.attrNames target_types);
+      description = ''
+        Defines the kind of target architecture system the device is.
+
+        This will automagically setup cross-compilation where possible.
+      '';
+    };
+  };
+
+  config = {
+    assertions = [
+      {
+        assertion = pkgs.targetPlatform.system == cfg.platform;
+        message = "pkgs.targetPlatform.system expected to be `aarch64-linux`, is `${pkgs.targetPlatform.system}`";
+      }
+    ];
+
+    nixpkgs.crossSystem = target_types.${cfg.platform};
+  };
+}