Qemu/kvm copy & paste

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1

So I am very new to NixOS as of today and testing it out in a VM in KVM on my Fedora host.
I am trying to get the copy/paste feature working in the VM but, so far, I have been unsuccessful. I have added the following packages to my config:

pkgs.spice
pkgs.spice-vdagent

And added the following services to my config:

services.spice-vdagentd.enable = true;
services.qemuGuest.enable = true;

Am I missing something?
If need be, I can post my complete config.

Also, for my understanding, after I make these changes and run sudo nixos-rebuild switch is there a need to reboot the machine to get the new config to work?
Thanks in advance from a complete noobie.

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2

You figured anything out here?:wink:

3

It’s quite tricky to set up SPICE correctly. First you need to add some options to QEMU:

  imports = [ <nixpkgs/nixos/modules/virtualisation/qemu-vm.nix> ];

  virtualisation.qemu.options = [
    "-vga qxl"
    "-spice port=5924,disable-ticketing=on"
    "-device virtio-serial -chardev spicevmc,id=vdagent,debug=0,name=vdagent"
    "-device virtserialport,chardev=vdagent,name=com.redhat.spice.0"
  ];

Then you have to enable the guest SPICE system-wide daemon

services.spice-vdagentd.enable = true

and, crucially, you need to make sure the per-session agent is started as part of your graphical session. For the latter, if you’re running a DE that implements the XDG autostart spec you’re done, otherwise you need to run spice-vdagent manually (after the X server, in your login session).

Finally, you start the VM as usual but no window will open, instead to connect to the VM you need a SPICE client, like spicy (pkgs.spice-gtk) and specify localhost:5924 (port specified in the qemu.options) as host.

After all of this you get:

  • automatic display resizing that follows the window size
  • shared clipboard
  • client mouse mode
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4

It doesn’t exist

5

https://search.nixos.org/options?query=virtualisation.qemu.options

6

When I use “sudo nixos-rebuild switch”, It gives me:

error: The option "virtualisation.qemu" does not exist.
7

Post your config.

(Post must be at least 20 characters.)

8

You need to import the qemu-vm.nix module:

  imports = [ <nixpkgs/nixos/modules/virtualisation/qemu-vm.nix> ];
9

After adding imports = [ <nixpkgs/nixos/modules/virtualisation/qemu-vm.nix> ]; , I got thrown into emergency mode, when rebooting I get

mounting nix-store on /nix/.ro-store...
[    1.560235] 9pnet_virtio: no channels available for device nix-store
mount: mounting nix-store on /mnt-root/nix/.ro-store failed No such file or directory

configuration.nix:

{ config, lib, pkgs, ... }:

let
  unstableTarball =
    fetchTarball
      https://github.com/NixOS/nixpkgs/archive/nixos-unstable.tar.gz;
in
{
  imports = [
    ./hardware-configuration.nix
    <nixpkgs/nixos/modules/virtualisation/qemu-vm.nix>
  ];

  nixpkgs.config = {
    packageOverrides = pkgs: {
      unstable = import unstableTarball {
        config = config.nixpkgs.config;
      };
    };
  };

  boot.loader.systemd-boot.enable = true;
  boot.loader.efi.canTouchEfiVariables = true;

  console = {
    font = "Lat2-Terminus16";
    useXkbConfig = true; # use xkb.options in tty.
  };

  services.xserver.enable = true;

  # Xmonad
  services.xserver.windowManager.xmonad = {
    enable = true;
    enableContribAndExtras = true;
  };

  # Disable default
  programs.nano.enable = false;
  services.xserver.excludePackages = with pkgs; [xterm];

  # Shell
  programs.zsh.enable = true;
  users.defaultUserShell = pkgs.zsh;

  # Configure keymap in X11
  services.xserver = {
    xkb.layout = "us";
    autoRepeatDelay = 200;
    autoRepeatInterval = 20;
  };

  users.users.test = {
    isNormalUser = true;
    extraGroups = [ "wheel" ]; # Enable ‘sudo’ for the user.
    packages = with pkgs; [
    ];
  };

  environment.systemPackages = with pkgs; [
    neovim
    wget
    zsh
    git
    gnumake
    python3
    unzip
    lua
    gcc
    nodePackages.pyright
    alacritty
    dmenu
    librewolf
    xsel
    xclip
  ];

  services.openssh.enable = true;
  system.stateVersion = "23.11"; # Did you read the comment?

}
10

That suggests adding virtualisation.mountHostNixStore = false;.

11

I added it, now I get:

mounting shared on /tmp/shared...
[    1.408774] 9pnet_virtio: no channels available for device shared
mount: mounting shared on /mnt-root/tmp/shared failed: No such file or directory
12

Huh. Looks like the qemu-vm.nix module just sets up a bunch of shared directories even though the documented default for virtualisation.sharedDirectories is { }.

Try virtualisation.sharedDirectories = lib.mkForce { };?

13

It works now when I use spice-vdagent, thanks.
But the automatic display resizing doesn’t work unfortunately, and I’m stuck with a 1024 x 768 resolution.

14

Thanks for all the info in this discussion I was able to get copy & paster working between a WSL NixOS distro & NixOS guest.

15

Okay, so in a nutshell, what is the required config to get copy&paste working now with qemu-vms?
Please, clearly indicate what’s configured on the host and what’s on the guest.

16

See

Note that this only works on X.org: redhat has pretty much abandoned SPICE after switching to Wayland.

17

Ah, I’m on wayland so that would explain my problems. Are you saying there’s no way to get c&p from host to guest to work at all with wayland and virtmanager?

18

I found an amusing workaround here; I don’t know if it’s vmware-specific either, but:

The other trick to copy from host to guest is…

  1. Copy the text on the host.
  2. Click the title bar of the window of the virtual machine without letting the mouse pass over the guest window.
  3. Click into the guest.
  4. Paste in the guest.

There’s also the workaround of using KDE connect (or even GitHub - andyholmes/valent: Connect, control and sync devices which uses the same protocol) to transfer data. Or a shared text file that you paste into.

(I’ve not tried these, just what I found.)

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