Re: Various issues when using multiple graphic outputs
On Fri, Sep 04, 2020 at 12:37:06PM +0200, Gerd Hoffmann wrote:
On Fri, Sep 04, 2020 at 12:05:08PM +0200, Christian Ehrhardt wrote:
> Hi,
> I've had continuous issues with this and wanted to reach out
> if that is a common issue everyone has or just me lacking a little
> detail on my setup.
> - QXL with multiple heads
> - works fine (so multi display in general seems fine for the
> involved components)
Yep.
> - VGA + QXL, QXL + Virtio, Virtio + QXL:
> - Guest only detects primary display
> - Can't convince X in the guest to use the second device as well
> - lspci lists both devices just fine
> - dmesg shows the kernel is initializing them, e.g. drm for virtio
As far I know xorg can't really deal with multiple display devices.
So typically you have a single device with multiple connectors, so
you can hook up multiple monitors.
IIRC, it Xorg can support multiple devices, but it is not zero-conf,
it needs a custom config file to be written, and has some functional
limitations compared to a multi-head layout. It has been at least 10+
years since I did something like this though :-)
In the virtual world qxl and virtio support multiple heads, so pick
one of these two and enable as many heads as you need. Also make sure
spice-agent is active in the guest, otherwise operating the mouse is a
PITA.
This is definitely the better approach to get zero-conf though.
Dunno how things are with wayland.
> - 2*QXL
> - X has issues to initialize on user login
> - no error in the log, just hung
The windows guest driver doesn't support qxl devices with multiple
outputs and expects one qxl device per head instead. So use this
one for windows guests.
HTH,
Gerd
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|