Multiple Displays - working in Catalina

[jpmorrison]

Qemu version:

qemu-system-x86_64 -version
QEMU emulator version 6.1.0
Copyright (c) 2003-2021 Fabrice Bellard and the QEMU Project developers

Display options:

-vga std -device secondary-vga

Result:

• Multiple displays in Spice viewer/Catalina

• Separate resolution settings in System Preferences

• Apple Bochs kext seems to be loaded

• Apple Cirrus driver probably just needs correct PCI vendor 0x1013 to load. See https://github.com/jpmorrison/OSX-Qemu/issues/2#issuecomment-951119176

                        <string>AppleCirrusGD5446FB</string>
                        <key>IOMatchCategory</key>
                        <string>IOFramebuffer</string>
                        <key>IOPCIPrimaryMatch</key>
                        <string>0x00001013&amp;0x0000FFFF</string>
                        <key>IOProbeScore</key>
                        <integer>30000</integer>
                        <key>IOProviderClass</key>
                        <string>IOPCIDevice</string>

Primary Display

Secondary Display

• Works but glitches after mode set - same issues as -device qxl
• qemu second display problem?
• video memory in qemu?
• Apple kext problem?
• qxl video glitches seem to go away after rebooting, maybe bochs does the same?

[jpmorrison]

• Reboot guest
• Fiddle with resolution on second display

Summary:

-vga std -device secondary-vga gives multiple displays in Spice remote-viewer. This may be the best option. I haven't noticed any speed differences compared to qxl - I don't think the Apple virtio driver supports qxl and just falls back to vga.

The second display is fixed after rebooting the guest.

[jpmorrison]

Not as good but still multiple displays. I think it is using AppleCirrusGD5446FB.

-device cirrus-vga,vgamem_mb=16 -device secondary-vga

• The Cirrus display is 800x600. No way to change resolution in Preferences
• After rebooting the displays are swapped.

• TODO: I'm still using virtio for OpenCoreBoot which doesn't save boot options. I really need to test with regular sata boot to see if any video options persist.

[jpmorrison]

Useful docs on video options in qemu https://www.kraxel.org/blog/2019/09/display-devices-in-qemu/

The following work with Catalina to varying degrees but always say 'kext not loaded" I think these are defaulting to VGA. I haven't noticed any speed difference with qxl.

-vga virtio
-device virtio-vga
-device qxl-vga
-device qxl