[Qemu-discuss] Monitor hotplug

[Timo Kaufmann]

Hi,



I want to simulate a monitor hotplug to a running linux guest. I want to

do this in order to automatically test a program that repsponds to an udev

event and configures randr (autorandr).



What I found:



- plain qemu: https://github.com/qemu/qemu/blob/master/docs/multiseat.txt

  I couldn't get this solution to work. Supposedly it should "just work" after

  systemd >222 (which I am using), but it didn't for me.

  Since it doesn't seem to support hotplug anyways, I didn't investigate 
further.



- using spice: https://people.freedesktop.org/~teuf/spice-doc/html/ch02s07.html

  This does support hotplug. I didn't get this to work either though:

  All the displays except the first one are greyed out in vinagre.

  Also I couldn't find any information on how to programmatically add another

  monitor without using a GUI.



For spice, I tried running qemu like this: (its intended as a nixos[1] test,

which is where the /nix/store paths come from):



```

qemu-kvm \

    -name vm \

    -m 1024 \

    -virtfs local,path=/nix/store,security_model=none,mount_tag=store \

    -virtfs local,path=$HOME/xchg,security_model=none,mount_tag=xchg \

    -virtfs local,path=$HOME/xchg,security_model=none,mount_tag=shared \

    -drive 
index=0,id=drive1,file=$HOME/vm.qcow2,if=virtio,cache=writeback,werror=report \

    -kernel 
/nix/store/an8and59kcxvcaln9qi5k5b5crxk1v4b-nixos-system-vm-17.09.git.1a8a95e879M/kernel
 \

    -initrd 
/nix/store/an8and59kcxvcaln9qi5k5b5crxk1v4b-nixos-system-vm-17.09.git.1a8a95e879M/initrd
 \

    -append 
"init=/nix/store/an8and59kcxvcaln9qi5k5b5crxk1v4b-nixos-system-vm-17.09.git.1a8a95e879M/init
 regInfo=/nix/store/knflc775wvpznh59n02ibma35dyncp8k-reginfo" \

    -vga qxl -device qxl \

    -spice port=5935,disable-ticketing

```



And then connect to it with `virt-viewer localhost:5905`.

However, the gui doesn't allow me to add a second display.





Can anybody help me?