derivation that produces /boot

modules/outputs.nix

@@ -12,6 +12,7 @@ in
   imports = [
     ./squashfs.nix
     ./outputs/vmroot.nix
+    ./outputs/extlinux.nix
   ];
   options = {
     system.outputs = {

modules/outputs/extlinux.nix

@@ -0,0 +1,37 @@
+{
+  config
+, pkgs
+, lib
+, ...
+}:
+let
+  inherit (lib) mkIf mkEnableOption mkOption types concatStringsSep;
+  cfg = config.boot.loader.extlinux;
+  o = config.system.outputs;
+  cmdline = concatStringsSep " " config.boot.commandLine;
+in {
+  options.system.outputs.extlinux = mkOption {
+    type = types.package;
+    # description = "";
+  };
+  options.boot.loader.extlinux.enable = mkEnableOption "extlinux";
+
+  config =  { # mkIf cfg.enable {
+    system.outputs.extlinux = pkgs.runCommand "extlinux" {} ''
+      mkdir $out
+      cd $out
+      ln -s ${o.dtb} dtb
+      ln -s ${o.initramfs} initramfs
+      gzip -9f < ${o.kernel} > kernel.gz
+      cat > extlinux.conf << _EOF
+      menu title Liminix
+      timeout 100
+      label Liminix
+        kernel kernel.gz
+        initrd initramfs
+        fdt dtb
+        append ${cmdline}
+      _EOF
+    '';
+  };
+}