Rename kboot-conf to petitboot and simplify a few things

hardkernel/odroid-m1/petitboot/default.nix

@@ -0,0 +1,75 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  cfg = config.boot.loader.petitboot;
+  args = "-g ${toString cfg.configurationLimit} -n ${config.hardware.deviceTree.name}";
+
+  # The installer used when running nixos-rebuild switch or similar
+  installer = pkgs.replaceVarsWith {
+    src = ./install-petitboot.sh;
+    replacements = {
+      bash = pkgs.bash;
+      path = lib.makeBinPath [
+        pkgs.coreutils
+        pkgs.gnused
+        pkgs.gnugrep
+      ];
+    };
+    name = "install-petitboot";
+    isExecutable = true;
+  };
+  # The installer used to write to SD card images
+  sdImageInstaller = pkgs.buildPackages.replaceVarsWith {
+    src = ./install-petitboot.sh;
+    replacements = {
+      bash = pkgs.buildPackages.bash;
+      path = lib.makeBinPath [
+        pkgs.buildPackages.coreutils
+        pkgs.buildPackages.gnused
+        pkgs.buildPackages.gnugrep
+      ];
+    };
+    name = "install-petitboot-sd-image";
+    isExecutable = true;
+  };
+in
+{
+  options = {
+    boot.loader.petitboot = {
+      enable = lib.mkOption {
+        default = false;
+        type = lib.types.bool;
+        description = ''
+          Whether to enable the Petitboot bootloader.
+        '';
+      };
+
+      configurationLimit = lib.mkOption {
+        default = 10;
+        example = 5;
+        type = lib.types.int;
+        description = ''
+          Maximum number of configurations to display when booting.
+        '';
+      };
+    };
+  };
+
+  config = lib.mkMerge[
+    (lib.mkIf config.boot.loader.petitboot.enable {
+      system.build.installBootLoader = lib.mkForce "${installer} ${args} -c";
+      system.boot.loader.id = "petitboot";
+    })
+
+    (lib.mkIf config.boot.loader.petitboot.enable && options ? sdImage {
+      sdImage.populateRootCommands = lib.mkForce ''
+        ${sdImageInstaller} ${args} -c ${config.system.build.toplevel} -d ./files/kboot.conf
+      ''
+    })
+  ];
+}