From 2faffd92fc81a6b850ac5df108e5c74b8e9c2551 Mon Sep 17 00:00:00 2001
From: Peter Esselius <pepp@me.com>
Date: Sun, 5 Oct 2025 16:22:14 +0200
Subject: [PATCH 1/2] Set qemu gui backend to cocoa on darwin

---
 lib/runners/qemu.nix              | 28 +++++++++++++---------
 nixos-modules/microvm/options.nix | 39 +++++++++++++++++++------------
 2 files changed, 41 insertions(+), 26 deletions(-)

diff --git a/lib/runners/qemu.nix b/lib/runners/qemu.nix
index 2a5e68ce..9f63425e 100644
--- a/lib/runners/qemu.nix
+++ b/lib/runners/qemu.nix
@@ -218,17 +218,23 @@ lib.warnIf (mem == 2048) ''
       "-drive" "id=store,format=raw,read-only=on,file=${storeDisk},if=none,aio=${aioEngine}"
       "-device" "virtio-blk-${devType},drive=store${lib.optionalString (devType == "pci") ",disable-legacy=on"}"
     ] ++
-    (if graphics.enable
-     then [
-      "-display" "gtk,gl=on"
-      "-device" "virtio-vga-gl"
-      "-device" "qemu-xhci"
-      "-device" "usb-tablet"
-      "-device" "usb-kbd"
-     ]
-     else [
-      "-nographic"
-     ]) ++
+       (if graphics.enable then (
+       let
+         displayArgs = {
+           cocoa = [
+             "-display" "cocoa" "-device" "virtio-gpu"
+           ];
+           gtk = [
+             "-display" "gtk,gl=on" "-device" "virtio-vga-gl"
+           ];
+         }.${graphics.backend};
+       in
+         displayArgs ++ [
+           "-device" "qemu-xhci"
+           "-device" "usb-tablet"
+           "-device" "usb-kbd"
+         ]
+       ) else [ "-nographic" ]) ++
     lib.optionals canSandbox [
       "-sandbox" "on"
     ] ++
diff --git a/nixos-modules/microvm/options.nix b/nixos-modules/microvm/options.nix
index 51703802..73330e39 100644
--- a/nixos-modules/microvm/options.nix
+++ b/nixos-modules/microvm/options.nix
@@ -475,21 +475,30 @@ in
       '';
     };
 
-    graphics.enable = mkOption {
-      type = types.bool;
-      default = false;
-      description = ''
-        Enable GUI support.
-
-        MicroVMs with graphics are intended for the interactive
-        use-case. They cannot be started through systemd jobs.
-
-        Support in Hypervisors:
-        - `qemu` starts a Gtk window with the framebuffer of the virtio-gpu
-      '';
-    };
-
-    graphics.socket = mkOption {
+     graphics.enable = mkOption {
+       type = types.bool;
+       default = false;
+       description = ''
+         Enable GUI support.
+
+         MicroVMs with graphics are intended for the interactive
+         use-case. They cannot be started through systemd jobs.
+
+         The display backend is chosen by `microvm.graphics.backend`.
+       '';
+     };
+
+     graphics.backend = mkOption {
+       type = types.enum [ "gtk" "cocoa" ];
+       default = if pkgs.stdenv.hostPlatform.isDarwin then "cocoa" else "gtk";
+       description = ''
+         QEMU display backend to use when `graphics.enable` is true.
+
+         Defaults to `cocoa` on Darwin hosts and `gtk` otherwise.
+       '';
+     };
+
+     graphics.socket = mkOption {
       type = types.str;
       default = "${hostName}-gpu.sock";
       description = ''

From 964848b15a601a8cd297d9ca4805f05aeddfc39b Mon Sep 17 00:00:00 2001
From: Peter Esselius <esselius@users.noreply.github.com>
Date: Wed, 22 Oct 2025 23:48:14 +0200
Subject: [PATCH 2/2] Add defaultText for microvm.graphics.backend option

Co-authored-by: Sandro <sandro.jaeckel@gmail.com>
---
 nixos-modules/microvm/options.nix | 1 +
 1 file changed, 1 insertion(+)

diff --git a/nixos-modules/microvm/options.nix b/nixos-modules/microvm/options.nix
index 73330e39..baa382be 100644
--- a/nixos-modules/microvm/options.nix
+++ b/nixos-modules/microvm/options.nix
@@ -491,6 +491,7 @@ in
      graphics.backend = mkOption {
        type = types.enum [ "gtk" "cocoa" ];
        default = if pkgs.stdenv.hostPlatform.isDarwin then "cocoa" else "gtk";
+       defaultText = lib.literalExpression ``if pkgs.stdenv.hostPlatform.isDarwin then "cocoa" else "gtk"``;
        description = ''
          QEMU display backend to use when `graphics.enable` is true.