[disko] add legacy option

I don't know if the grub device is right

machines/modules/disko/default.nix

@@ -20,6 +20,11 @@ in
       default = true;
       description = "Allows encryption to be disabled for testing";
     };
+    legacy = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      description = "Enable legacy boot (bios)";
+    };
     devNodes = lib.mkOption {
       type = lib.types.str;
       default = "/dev/disk/by-id/";
@@ -81,7 +86,25 @@ in
     };
   };
 
-  config = lib.mkIf cfg.enable {
+  config = lib.mkMerge [
+    (lib.mkIf (cfg.enable && !cfg.legacy) {
+      boot = {
+        loader.systemd-boot.enable = true;
+        loader.efi.canTouchEfiVariables = true;
+        supportedFilesystems = [ "vfat" "zfs" ];
+      };
+      fileSystems."/boot".neededForBoot = true;
+    })
+    (lib.mkIf (cfg.enable && cfg.legacy) {
+      boot.loader.grub = {
+        enable = true;
+        device = "/dev/${cfg.root.disk0}-part1";
+        efiSupport = false;
+        enableCryptodisk = cfg.encryption;
+        zfsSupport = true;
+      };
+    })
+    (lib.mkIf cfg.enable {
       networking.hostId = cfg.hostId;
       disko.devices = {
         disk = lib.mkMerge [
@@ -92,7 +115,7 @@ in
               content = {
                 type = "gpt";
                 partitions = {
-                ESP = {
+                  ESP = lib.mkIf (!cfg.legacy) {
                     size = "1024M";
                     type = "EF00";
                     content = {
@@ -102,6 +125,10 @@ in
                       mountOptions = [ "umask=0077" ];
                     };
                   };
+                  boot = lib.mkIf cfg.legacy {
+                    size = "1024M";
+                    type = "EF02";
+                  };
                   encryptedSwap = {
                     size = cfg.root.swap;
                     content =  {
@@ -270,9 +297,9 @@ in
 
       fileSystems."/".neededForBoot = true;
       fileSystems."/etc".neededForBoot = true;
-    fileSystems."/boot".neededForBoot = true;
       fileSystems."/var".neededForBoot = true;
       fileSystems."/home".neededForBoot = true;
       fileSystems."/nix".neededForBoot = true;
-  };
+    })
+  ];
 }

machines/modules/malobeo/initssh.nix

@@ -26,13 +26,9 @@ in
   
   config = lib.mkIf (cfg.enable && config.malobeo.disks.encryption) {
     boot = {
-      loader.systemd-boot.enable = true;
-      loader.efi.canTouchEfiVariables = true;
-      supportedFilesystems = [ "vfat" "zfs" ];
       zfs = {
         forceImportAll = true;
         requestEncryptionCredentials = true;
-        
       };
       initrd = {
         availableKernelModules = cfg.ethernetDrivers;