nixos on hyperv: load modules and set video mode

nixos/modules/virtualisation/hyperv-guest.nix

@@ -9,10 +9,33 @@ in {
   options = {
     virtualisation.hypervGuest = {
       enable = mkEnableOption "Hyper-V Guest Support";
+
+      videoMode = mkOption {
+        type = types.str;
+        default = "1152x864";
+        example = "1024x768";
+        description = ''
+          Resolution at which to initialize the video adapter.
+
+          Supports screen resolution up to Full HD 1920x1080 with 32 bit color
+          on Windows Server 2012, and 1600x1200 with 16 bit color on Windows
+          Server 2008 R2 or earlier.
+        '';
+      };
     };
   };
 
   config = mkIf cfg.enable {
+    boot = {
+      initrd.kernelModules = [
+        "hv_balloon" "hv_netvsc" "hv_storvsc" "hv_utils" "hv_vmbus"
+      ];
+
+      kernelParams = [
+        "video=hyperv_fb:${cfg.videoMode}"
+      ];
+    };
+
     environment.systemPackages = [ config.boot.kernelPackages.hyperv-daemons.bin ];
 
     security.rngd.enable = false;