Initialization failure related to GBM Backend on NixOS

[barthofu]

Problem Description

When attempting to launch Hyprland directly from a TTY, the process fails with a critical error related to GBM/DRM graphics backend initialization. The application is unable to acquire a rendering allocator.

It was running smoothly before but the error appeared when I tried to update my system and packages ;

• from NixOS 24.05 to NixOS 25.05
• update of my flake inputs, especially the unstable channel input (which haven't been updated since a while tbh)

Critical Error Logs

[ERR] [AQ] Wayland backend cannot start: wl_display_connect failed (is a wayland compositor running?)
[ERR] [AQ] Couldn't open a GBM device at fd 30
[ERR] [AQ] Cannot create a GBM Allocator: gbm failed to create a device.
[CRITICAL] [AQ] Cannot open backend: no allocator available
[CRITICAL] m_pAqBackend couldn't start! This usually means aquamarine could not find a GPU or encountered some issues. Make sure you're running either on a tty or on a Wayland session, NOT an X11 one.

Environment Details

• OS: NixOS (unstable channel)
• Composer: Hyprland (launched via TTY)
• Hardware: Lenovo laptop with both iGPU (Intel i5-13500H) and discrete mobile GPU (RTX 3050)

Configuration

Here's related extracts from my NixOS configuration:

• flake

inputs = {
  unstable = {
    url = "github:NixOS/nixpkgs/nixos-unstable";
  };

  nixpkgs = {
    follows = "unstable";
  };

  home-manager = {
    url = "github:nix-community/home-manager/master";
    inputs.nixpkgs.follows = "nixpkgs";
  };

  hyprland = {
    url = "github:hyprwm/Hyprland";
    inputs.nixpkgs.follows = "nixpkgs";
  };
}

• hyprland (home-manager)

wayland.windowManager.hyprland = {
  enable = true;
  xwayland.enable = true;
  package = null;
  portalPackage = null;

  plugins = [
    inputs.hyprland-virtual-desktops.packages.${pkgs.system}.virtual-desktops
  ];

  extraConfig = ''
    source = ~/.config/hypr/hyprland-source.conf
  '' + ''
    ${if cliphistEnabled then "exec-once = cliphist wipe; wl-paste --watch cliphist store" else ""}
  '' + ''
    plugin {
      virtual-desktops {
        names = 1, 2, 3, 4, 5, 6, 7, 8, 9
        cycleworkspaces = 1
        rememberlayoput = size
        notifyinit = 0
        verbose_logging = 0
      }
    }
  '';

  systemd = {
    variables = ["--all"];
    extraCommands = [
      "systemctl --user stop graphical-session.target"
      "systemctl --user start hyprland-session.target"
    ];
  };
};

• hyprland (nixos)

programs.hyprland = {
  enable = true;
  package = inputs.hyprland.packages.${pkgs.stdenv.hostPlatform.system}.hyprland;
  portalPackage = inputs.hyprland.packages.${pkgs.stdenv.hostPlatform.system}.xdg-desktop-portal-hyprland;
};

• graphics

nixpkgs.config.packageOverrides = pkgs: {
  intel-vaapi-driver = pkgs.intel-vaapi-driver.override { enableHybridCodec = true; };
};

hardware.graphics = {
  enable = true;
  enable32Bit = true;
  package = pkgs.mesa;
  package32 = pkgs.pkgsi686Linux.mesa;

  extraPackages = with pkgs; [
    intel-media-driver # LIBVA_DRIVER_NAME=iHD
    intel-vaapi-driver # LIBVA_DRIVER_NAME=i965 (older but works better for Firefox/Chromium)
    libvdpau-va-gl
    mesa
    mesa-demos
  ];
};

environment.variables = {
  GBM_BACKENDS_PATH = "/run/opengl-driver/lib";
};

Verification Steps (Unsuccessful)

• User permissions: The user is a member of the video group, and the render group was explicitly added to the user's extraGroups and applied via nixos-rebuild switch. The GBM error persists.
• Driver conflicts: The intel-vaapi-driver was temporarily removed to eliminate potential conflicts between the iHD and i965 drivers. The issue remains.
• DRM Variable Test: The launch was attempted after setting the AQ_DRM_DEVICES env in the Hyprland config. The failure persisted.