uimage: make fit optional

modules/base.nix

@@ -47,6 +47,10 @@ in {
         default = [];
         description = "Kernel command line";
       };
+      imageFormat = mkOption {
+        type = types.enum ["fit" "uimage"];
+        default = "uimage";
+      };
       tftp = {
         loadAddress = mkOption {
           type = types.str;

modules/outputs.nix

@@ -78,6 +78,7 @@ in
       uimage = liminix.builders.uimage {
         commandLine = concatStringsSep " " config.boot.commandLine;
         inherit (config.hardware) loadAddress entryPoint;
+        inherit (config.boot) imageFormat;
         inherit kernel;
         inherit dtb;
       };