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I have installed Ubuntu Desktop 16.04 with KVM in a bare metal server. Then, using virt-manager, I have created a brand new Ubuntu Desktop 16.04 guest with a single QXL Video device and a Spice server. I'm accessing this VM using virt-viewer (Remote Viewer) on a Windows desktop machine. My understanding is that Spice should provide as many as four virtual displays to enable a multiple monitor environment on the client side. However, when I select view->displays in the virt-viewer, displays 2-4 are grayed out and not selectable. The command 'xrandr' performed on the guest indicates that Virtual-0 is connected/primary and Virtual-1 through -3 are disconnected. I can add modes to Virtual-1 using

xrander --addmode Virtual-1 1024x768

but when I try to connect it using the following command

xrander --output Virtual-1 -d 1 --mode 1024x768

I get 'Can't open display 1'. Is the problem that I need to activate more X-displays? If so, how do I do that?

The server I'm using is a Dell R210 II with only the default Intel graphics and only one physical monitor connected, but my understanding is that these are virtual graphics devices, not pass-thrus, so the hardware shouldn't matter. Is that wrong? Any helps is appreciated!

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  • Solved the initial problem (see answer below regarding spice-vdagent install). Now I have a new problem. After the host and the guest restarted, I get the following behavior. I can initially connect to the guest using virt-viewer and it opens a single screen. When I try to select the additional screen, it lets me, but the first screen turns black and the second screen says "Waiting for display 2". After that, I can no longer access any screens for the guest, even from the host, so I think I killed all the displays. I can still ssh. restarting spice-vdagent doesn't help. Jan 20, 2018 at 14:09
  • I ended up recreating the VM and running spice-vdagent within the guest and everything seems to be working fine now. I must have messed something up with the old VM, so I'd consider the below answer suitable. Jan 21, 2018 at 16:05

3 Answers 3

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It turns out that I did not know I needed to install spice-vdagent within the guest machine. Doing that enabled me to select the additional displays. That initially fixed the problem. Now I have a new problem, so I was leery about posting this as a solution until I confirm they are unrelated. See comments above.

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In Proxmox KVM, I am doing everything properly, have spice-vdagent installed in VM Ubuntu 20.04 LTS Desktop (gnome), but still the system won't see in display settings any extra monitor, and clicking display 2 in remote-viewer doesn't do anything.

I've seen that people have had this problem with different Ubuntu versions (ranging probably to even 16.04 LTS already then), and I have encountered that this might be problem with HWE kernel, so perhaps reinstalling to GA kernel can fix the problem:

https://stafwag.github.io/blog/blog...resolution-on-a-kvm-virtual-machine-with-qxl/

https://askubuntu.com/a/1011440/702332

I haven't tried that but I will give it a shot some day in the future.

I also reported the case here and in other places:

https://forum.proxmox.com/threads/spice-dual-monitor-from-windows-7-guest.52296/

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@Tomeg, I had the same problem as yourself selecting the second display, using Proxmox Virtual Environment 6.4-8, Ubuntu Guest with display configured as SPICE Dual Monitor (qxl) and using virt-viewer (latest as of posting).

Note: It was originally working, then stopped working after disabling it and powering the guest off.

This worked for me:

  1. Ran xrandr from the shell on the Ubuntu 20.4 guest, this showed me that the Virtual-2 to Virtual-4 displays were disconnected.

  2. Then ran the following to enable the Virtual-2 display and the second display appeared (automatically enabled within virt-viewer):

xrandr --addmode Virtual-2 1920x1080
xrandr --output Virtual-2 --mode 1920x1080 --right-of Virtual-1

Additional Note: If I now disable the second display from within virt-viewer and power the guest off, I have to follow the same process to get it working again.

Hope this helps..

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