Set qemu gui backend to cocoa on darwin

[esselius]

No description provided.

[SuperSandro2000]

Can you provide some context why cocoa is better? I don't know much about MacOS.

[esselius]

Can you provide some context why cocoa is better? I don't know much about MacOS. @SuperSandro2000

Ah yes sorry for low detail, I'll bring in as much relevant detail as I can then.

qemu in nixpkgs isn't built with gtk on darwin by default:

$ qemu-system-aarch64 -h|grep cocoa -C 4
Display options:
-display spice-app[,gl=on|off]
-display vnc=<display>[,<optargs>]
-display curses[,charset=<encoding>]
-display cocoa[,full-grab=on|off][,swap-opt-cmd=on|off]
              [,show-cursor=on|off][,left-command-key=on|off]
              [,full-screen=on|off][,zoom-to-fit=on|off]
-display dbus[,addr=<dbusaddr>]
             [,gl=on|core|es|off][,rendernode=<file>]
-display none
                select display backend type
                The default display is equivalent to
                "-display cocoa"

So microvm.graphics.enable = true; gets you a:
microvm@example: -display gtk,gl=on: Parameter 'type' does not accept value 'gtk'.

If you do vmHostPackages.qemu.override { gtkSupport = true; }, you end up with a:
microvm@example: OpenGL support was not enabled in this build of QEMU.

If you also override openGLSupport = true;, you end up with unsupported host platform build error (libdrm not supporting darwin).

I backed down and did -display gtk,gl=on -> -display gtk, which gets you a:
microvm@example: -device virtio-vga-gl: 'virtio-vga-gl' is not a valid device model name

These are de supported display devices:

$ qemu-system-aarch64 -machine virt -device help
....
Display devices:
name "apple-gfx-pci", bus PCI, desc "macOS Paravirtualized Graphics PCI Display Controller"
name "ati-vga", bus PCI
name "bochs-display", bus PCI
name "cirrus-vga", bus PCI, desc "Cirrus CLGD 54xx VGA"
name "dm163", desc "DM163 8x3-channel constant current LED driver"
name "led", desc "LED"
name "ramfb", bus System, desc "ram framebuffer standalone device"
name "secondary-vga", bus PCI
name "ssd0323", bus SSI
name "VGA", bus PCI
name "virtio-gpu-device", bus virtio-bus
name "virtio-gpu-pci", bus PCI, alias "virtio-gpu"
...

apple-gfx-pci is for macos guests and virtio-gpu-pci does 3D accel for linux guests.

In the end, using gtk + virtio-gpu doesn't make a separate vm window show up, staying tty-only, while using cocoa does make a window pop up 🤷‍♂️ So this seemed like the most acceptable compromise, no overrides and 3d-accel support on both darwin and linux