Merge pull request #433 from bjackman/firecracker-driveioengine

firecracker: Add option to set up io_engine for drives

Author: SuperSandro2000

lib/runners/firecracker.nix

@@ -38,7 +38,7 @@ let
       path_on_host = storeDisk;
       is_root_device = false;
       is_read_only = true;
-      io_engine = "Async";
+      io_engine = microvmConfig.firecracker.driveIoEngine;
     } ] ++ map ({ image, serial, direct, readOnly, ... }:
       lib.warnIf (serial != null) ''
         Volume serial is not supported for firecracker
@@ -50,7 +50,7 @@ let
         path_on_host = image;
         is_root_device = false;
         is_read_only = readOnly;
-        io_engine = "Async";
+        io_engine = microvmConfig.firecracker.driveIoEngine;
       }) volumes;
     network-interfaces = map ({ type, id, mac, ... }:
       if type == "tap"

nixos-modules/microvm/options.nix

@@ -590,6 +590,12 @@ in
       description = "Custom CPU template passed to firecracker.";
     };
 
+    firecracker.driveIoEngine = mkOption {
+      type = types.enum [ "Async" "Sync" ];
+      default = "Async";
+      description = "Type of IO engine to use for Firecracker drives (disks).";
+    };
+
     prettyProcnames = mkOption {
       type = types.bool;
       default = true;