Displaylink

DisplayLink monitors

In order to use Displaylink monitors over USB, such as the ASUS MB16AC, the displaylink driver needs to be installed:

$ services.xserver.videoDrivers = [ "displaylink" "modesetting" ];

The module `nixos/modules/hardware/video/displaylink.nix` should also work for wlroots compositors.

Since these drivers depend on binary unfree blobs, you will need to first add it to your nix-store. Go to https://www.displaylink.com/downloads/ubuntu to get the appropriate driver version and note the download URL you get after accepting the EULA. The currently expected version for the driver can be found under: https://www.synaptics.com/products/displaylink-graphics/downloads/ubuntu-5.8?filetype=exe.

Then (example):

$ nix-prefetch-url --name displaylink-600.zip https://www.synaptics.com/sites/default/files/exe_files/2024-05/DisplayLink%20USB%20Graphics%20Software%20for%20Ubuntu6.0-EXE.zip

Xserver

Connecting a second external monitor

In order to add a second external monitor you can add the following to your configuration:

services.xserver.displayManager.sessionCommands = ''
    ${lib.getBin pkgs.xorg.xrandr}/bin/xrandr --setprovideroutputsource 2 0
'';

DisplayLink Driver and Wayland

At first add displayLink driver to nix store as above described.

evdi module

You probably will need the `evdi` module

boot = {
  extraModulePackages = [ config.boot.kernelPackages.evdi ];
  initrd = {
    # List of modules that are always loaded by the initrd.
    kernelModules = [
      "evdi"
    ];
  };
};

Gnome Wayland

Install displayLink package

environment.systemPackages = with pkgs; [
  displaylink
];

Define videoDrivers

services.xserver.videoDrivers = [ "displaylink" ];

Add dlm service

systemd.services.dlm.wantedBy = [ "multi-user.target" ];

KDE Plasma

Apparently KDE Plasma (Wayland) requires a slight different approach.

Esnure you properly enabled wayland session

environment.variables = {
  KWIN_DRM_PREFER_COLOR_DEPTH = "24";
};

services = {
  desktopManager.plasma6 = {
    enable = true;
  };
  displayManager = {
    sddm = {
      enable = true;
      wayland.enable = true;
    };
    defaultSession = "plasma";
  };

};

Install displayLink package

environment.systemPackages = with pkgs; [
  displaylink
];

Instead of dlm setup display-link server as follows:

# --- THIS IS THE CRUCIAL PART FOR ENABLING THE SERVICE ---
systemd.services.displaylink-server = {
  enable = true;
  # Ensure it starts after udev has done its work
  requires = [ "systemd-udevd.service" ];
  after = [ "systemd-udevd.service" ];
  wantedBy = [ "multi-user.target" ]; # Start at boot
  # *** THIS IS THE CRITICAL 'serviceConfig' BLOCK ***
  serviceConfig = {
    Type = "simple"; # Or "forking" if it forks (simple is common for daemons)
    # The ExecStart path points to the DisplayLinkManager binary provided by the package
    ExecStart = "${pkgs.displaylink}/bin/DisplayLinkManager";
    # User and Group to run the service as (root is common for this type of daemon)
    User = "root";
    Group = "root";
    # Environment variables that the service itself might need
    # Environment = [ "DISPLAY=:0" ]; # Might be needed in some cases, but generally not for this
    Restart = "on-failure";
    RestartSec = 5; # Wait 5 seconds before restarting
  };
};