nixos/binfmt: move systemd-binfmt.service to binfmt module

nixos/modules/system/boot/binfmt.nix

@@ -268,9 +268,10 @@ in {
       mkdir -p -m 0755 /run/binfmt
       ${lib.concatStringsSep "\n" (lib.mapAttrsToList activationSnippet config.boot.binfmt.registrations)}
     '';
-    systemd.additionalUpstreamSystemUnits = lib.mkIf (config.boot.binfmt.registrations != {})
-      [ "proc-sys-fs-binfmt_misc.automount"
-        "proc-sys-fs-binfmt_misc.mount"
-      ];
+    systemd.additionalUpstreamSystemUnits = lib.mkIf (config.boot.binfmt.registrations != {}) [
+      "proc-sys-fs-binfmt_misc.automount"
+      "proc-sys-fs-binfmt_misc.mount"
+      "systemd-binfmt.service"
+    ];
   };
 }

nixos/modules/system/boot/systemd.nix

@@ -164,7 +164,6 @@ let
       "systemd-timedated.service"
       "systemd-localed.service"
       "systemd-hostnamed.service"
-      "systemd-binfmt.service"
       "systemd-exit.service"
       "systemd-update-done.service"
     ] ++ optionals config.services.journald.enableHttpGateway [
@@ -1056,7 +1055,6 @@ in
     systemd.targets.local-fs.unitConfig.X-StopOnReconfiguration = true;
     systemd.targets.remote-fs.unitConfig.X-StopOnReconfiguration = true;
     systemd.targets.network-online.wantedBy = [ "multi-user.target" ];
-    systemd.services.systemd-binfmt.wants = [ "proc-sys-fs-binfmt_misc.mount" ];
     systemd.services.systemd-importd.environment = proxy_env;
 
     # Don't bother with certain units in containers.

nixos/tests/all-tests.nix

@@ -304,6 +304,7 @@ in
   syncthing-relay = handleTest ./syncthing-relay.nix {};
   systemd = handleTest ./systemd.nix {};
   systemd-analyze = handleTest ./systemd-analyze.nix {};
+  systemd-binfmt = handleTestOn ["x86_64-linux"] ./systemd-binfmt.nix {};
   systemd-boot = handleTestOn ["x86_64-linux"] ./systemd-boot.nix {};
   systemd-confinement = handleTest ./systemd-confinement.nix {};
   systemd-timesyncd = handleTest ./systemd-timesyncd.nix {};

nixos/tests/systemd-binfmt.nix

@@ -0,0 +1,24 @@
+# Teach the kernel how to run armv7l and aarch64-linux binaries,
+# and run GNU Hello for these architectures.
+import ./make-test-python.nix ({ pkgs, ... }: {
+  name = "systemd-binfmt";
+  machine = {
+    boot.binfmt.emulatedSystems = [
+      "armv7l-linux"
+      "aarch64-linux"
+    ];
+  };
+
+  testScript = let
+    helloArmv7l = pkgs.pkgsCross.armv7l-hf-multiplatform.hello;
+    helloAarch64 = pkgs.pkgsCross.aarch64-multiplatform.hello;
+  in ''
+    machine.start()
+    assert "world" in machine.succeed(
+        "${helloArmv7l}/bin/hello"
+    )
+    assert "world" in machine.succeed(
+        "${helloAarch64}/bin/hello"
+    )
+  '';
+})