nixos/systemd-boot: allow for bootspec-less generations

Generation built with old versions of NixOS with no bootspec
support may still be present on the system and must be
accounted for.

nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py

@@ -88,9 +88,20 @@ def write_loader_conf(profile: str | None, generation: int, specialisation: str
 
 
 def get_bootspec(profile: str | None, generation: int) -> BootSpec:
-    boot_json_path = os.path.realpath("%s/%s" % (system_dir(profile, generation, None), "boot.json"))
+    system_directory = system_dir(profile, generation, None)
-    boot_json_f = open(boot_json_path, 'r')
+    boot_json_path = os.path.realpath("%s/%s" % (system_directory, "boot.json"))
-    bootspec_json = json.load(boot_json_f)
+    if os.path.isfile(boot_json_path):
+        boot_json_f = open(boot_json_path, 'r')
+        bootspec_json = json.load(boot_json_f)
+    else:
+        boot_json_str = subprocess.check_output([
+        "@bootspecTools@/bin/synthesize",
+        "--version",
+        "1",
+        system_directory,
+        "/dev/stdout"],
+        universal_newlines=True)
+        bootspec_json = json.loads(boot_json_str)
     return bootspec_from_json(bootspec_json)
 
 def bootspec_from_json(bootspec_json: Dict) -> BootSpec:

nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix

@@ -16,6 +16,8 @@ let
 
     systemd = config.systemd.package;
 
+    bootspecTools = pkgs.bootspec;
+
     nix = config.nix.package.out;
 
     timeout = optionalString (config.boot.loader.timeout != null) config.boot.loader.timeout;

nixos/tests/systemd-boot.nix

@@ -277,4 +277,20 @@ in
       machine.wait_for_unit("multi-user.target")
     '';
   };
+
+  no-bootspec = makeTest
+    {
+      name = "systemd-boot-no-bootspec";
+      meta.maintainers = with pkgs.lib.maintainers; [ julienmalka ];
+
+      nodes.machine = {
+        imports = [ common ];
+        boot.bootspec.enable = false;
+      };
+
+      testScript = ''
+        machine.start()
+        machine.wait_for_unit("multi-user.target")
+      '';
+    };
 }

pkgs/tools/misc/bootspec/default.nix

@@ -1,6 +1,7 @@
 { lib
 , rustPlatform
 , fetchFromGitHub
+, fetchpatch
 }:
 rustPlatform.buildRustPackage rec {
   pname = "bootspec";
@@ -13,6 +14,17 @@ rustPlatform.buildRustPackage rec {
     hash = "sha256-5IGSMHeL0eKfl7teDejAckYQjc8aeLwfwIQSzQ8YaAg=";
   };
 
+  patches = [
+    # https://github.com/DeterminateSystems/bootspec/pull/127
+    # Fixes the synthesize tool for aarch64-linux
+    (fetchpatch {
+      name = "aarch64-support.patch";
+      url = "https://github.com/DeterminateSystems/bootspec/commit/1d0e925f360f0199f13422fb7541225fd162fd4f.patch";
+      sha256 = "sha256-wU/jWnOqVBrU2swANdXbQfzRpNd/JIS4cxSyCvixZM0=";
+    })
+
+  ];
+
   cargoHash = "sha256-eGSKVHjPnHK7WyGkO5LIjocNGHawahYQR3H5Lgk1C9s=";
 
   meta = with lib; {