Missing sddm.conf with KDE Plasma 6 and wayland

Hi everyone,

I have a strange behaviour with KDE / SDDM, maybe a bug. I did two separate fresh installations out of the officials ISO. One inside a VM, one on my desktop pc and I can confirm this on both of them. I upgraded to NixOS unstable and KDE Plasma 6. Everything is fine as long as I not enable wayland SDDM with:

services.displayManager.sddm.wayland.enable = true;

With the standard config:

services.xserver.displayManager.sddm.enable = true;

there is a /etc/sddm.confwhich links to /etc/static/sddm.conf and links from there into /nix/store. As soon I change this to the above wayland.enable = true there is none anymore. Login procedures still works but without any themed splash screen.

This behaviour is reproducible on both systems.

Here you find the complete configuration.nix:

# Edit this configuration file to define what should be installed on
# your system.  Help is available in the configuration.nix(5) man page
# and in the NixOS manual (accessible by running ‘nixos-help’).

{ config, pkgs, ... }:

{
  imports =
    [ # Include the results of the hardware scan.
      ./hardware-configuration.nix
    ];

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

  networking.hostName = "nixos"; # Define your hostname.
  # networking.wireless.enable = true;  # Enables wireless support via wpa_supplicant.

  # Configure network proxy if necessary
  # networking.proxy.default = "http://user:password@proxy:port/";
  # networking.proxy.noProxy = "127.0.0.1,localhost,internal.domain";

  # Enable networking
  networking.networkmanager.enable = true;

  # Set your time zone.
  time.timeZone = "Europe/Berlin";

  # Select internationalisation properties.
  i18n.defaultLocale = "en_US.UTF-8";

  i18n.extraLocaleSettings = {
    LC_ADDRESS = "de_DE.UTF-8";
    LC_IDENTIFICATION = "de_DE.UTF-8";
    LC_MEASUREMENT = "de_DE.UTF-8";
    LC_MONETARY = "de_DE.UTF-8";
    LC_NAME = "de_DE.UTF-8";
    LC_NUMERIC = "de_DE.UTF-8";
    LC_PAPER = "de_DE.UTF-8";
    LC_TELEPHONE = "de_DE.UTF-8";
    LC_TIME = "de_DE.UTF-8";
  };

  # Enable the X11 windowing system.
  services.xserver.enable = true;

  # Enable the KDE Plasma Desktop Environment.
  #services.xserver.displayManager.sddm.enable = true;
  #services.xserver.desktopManager.plasma6.enable = true;
  services.displayManager.sddm.wayland.enable = true;
  #services.displayManager.sddm.enable = true;
  services.desktopManager.plasma6.enable = true;

  # Configure keymap in X11
  #services.xserver = {
  #  layout = "de";
  #  xkbVariant = "";
  #};
  services.xserver.xkb = {
    layout = "de";
    variant = "";
  };

  # Configure console keymap
  console.keyMap = "de";

  # Enable CUPS to print documents.
  services.printing.enable = true;

  # Enable sound with pipewire.
  sound.enable = true;
  hardware.pulseaudio.enable = false;
  security.rtkit.enable = true;
  services.pipewire = {
    enable = true;
    alsa.enable = true;
    alsa.support32Bit = true;
    pulse.enable = true;
    # If you want to use JACK applications, uncomment this
    #jack.enable = true;

    # use the example session manager (no others are packaged yet so this is enabled by default,
    # no need to redefine it in your config for now)
    #media-session.enable = true;
  };

  # Enable touchpad support (enabled default in most desktopManager).
  # services.xserver.libinput.enable = true;

  # Define a user account. Don't forget to set a password with ‘passwd’.
  users.users.xkrenzsim = {
    isNormalUser = true;
    description = "Simon Krenz";
    extraGroups = [ "networkmanager" "wheel" ];
    packages = with pkgs; [
      kate
    #  thunderbird
    ];
  };

  # Install firefox.
  programs.firefox.enable = true;

  # Allow unfree packages
  nixpkgs.config.allowUnfree = true;

  # List packages installed in system profile. To search, run:
  # $ nix search wget
  environment.systemPackages = with pkgs; [
    brave
    kdePackages.kdeconnect-kde
    xwaylandvideobridge
    vim # Do not forget to add an editor to edit configuration.nix! The Nano editor is also installed by default.
  #  wget
  ];

  programs.kdeconnect.enable = true;

  # Some programs need SUID wrappers, can be configured further or are
  # started in user sessions.
  # programs.mtr.enable = true;
  # programs.gnupg.agent = {
  #   enable = true;
  #   enableSSHSupport = true;
  # };

  # List services that you want to enable:

  # Enable the OpenSSH daemon.
  # services.openssh.enable = true;

  # Open ports in the firewall.
  # networking.firewall.allowedTCPPorts = [ ... ];
  # networking.firewall.allowedUDPPorts = [ ... ];
  # Or disable the firewall altogether.
  # networking.firewall.enable = false;

  # This value determines the NixOS release from which the default
  # settings for stateful data, l file locations and database versions
  # on your system were taken. It‘s perfectly fine and recommended to leave
  # this value at the release version of the first install of this system.
  # Before changing this value read the documentation for this option
  # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
  system.stateVersion = "23.11"; # Did you read the comment?

}

Ok thanks to a friend the problem was, that this line:

services.displayManager.sddm.wayland.enable = true;

does not replaces this line

services.displayManager.sddm.enable = true;

it is an addition.

1 Like

services.displayManager.sddm.wayland.enable = true just enables wayland in sddm, which does nothing when disabling in overall sddm gets disabled.

But that also explains a lot why i did not face the issue when building your config and wasnt able to reproduce in my tests.

If you face other issues i recommend to fully document/write down changes you are applying and try to avoid indirect assumptions, you just said in both threads that you enable services.displayManager.sddm.wayland.enable = true; but never that you set services.displayManager.sddm.enable = false; at the same time.

It would have been super clear to people knowing the code that this will lead in not having sddm at all, if it would have been spoken out… :slight_smile:

Yeah my bad! Next time it will be more precise.