Various issues when using multiple graphic outputs
Daniel P. Berrangé
berrange at redhat.com
Fri Sep 4 10:46:38 UTC 2020
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 :|
More information about the libvir-list
mailing list