Displays

Noctalia Greeter uses its bundled wlroots compositor to configure displays. Put the settings on this page under [output] in /var/lib/noctalia-greeter/greeter.toml. On NixOS, use services.displayManager.noctalia-greeter.settings.output with the nixpkgs module or programs.noctalia-greeter.settings.output with the project flake.

• Find connector names
• Choose which monitors show the greeter
• Arrange multiple monitors
• Match the desktop output mode
• Rotate an output
• Scale the interface
• Blank displays when idle
• Apply changes

Find connector names

Run this from a graphical Wayland session:

noctalia-greeter outputs

Use the connector names it prints, such as DP-1 or HDMI-A-1, in the settings below.

Choose which monitors show the greeter

By default, the greeter shows the same login interface on every connected monitor. Each display uses its own resolution and scale.

To show it on only one monitor, pin that connector:

[output]
name = "DP-2"

The compositor disables all other connectors at the KMS level while the greeter is running. If name is empty, missing, invalid, or refers to a disconnected monitor, the greeter falls back to all connected outputs.

Arrange multiple monitors

Without an explicit layout, outputs are placed from left to right in connector name order. If that does not match the physical arrangement, set their logical positions:

[output]
layout = "DP-1:0,0; DP-2:2560,0"
scales = "DP-1:1; DP-2:1"

layout coordinates are logical pixels. Use matching per-output scales so the configured edges remain adjacent and the pointer can move naturally between monitors. When layout is set but a connector has no matching scale, that connector uses scale 1.0 instead of automatic DPI scaling. A global scale setting overrides all per-output scales.

Noctalia can copy layout, transform, and effective scale values from the desktop session through xdg-output. It records a layout only when multiple ready outputs report distinct positions; transforms and scales need at least one ready output. See Sync with Noctalia. Values declared in greeter.toml take precedence over synchronized values in sync.toml.

Match the desktop output mode

By default, the compositor uses each display’s EDID-preferred resolution and then selects the highest advertised refresh rate at that size. If this differs from the desktop session, the display may flash or modeset during login.

Set both width and height to request a particular resolution:

[output]
name = "DP-2"
width = 5120
height = 2160

Both values are required and must be positive. A partial or invalid override is ignored. If the display does not advertise the requested size, the compositor logs a warning and falls back to the preferred-resolution behavior. At the requested size, it still chooses the highest advertised refresh rate.

Note

width and height select the physical DRM mode in pixels. They are separate from scale, which changes the size of the greeter interface. Mode dimensions are selected before any output rotation is applied.

Match the resolution to the desktop session to avoid an unnecessary resolution change when logging in.

Rotate an output

For a portrait or flipped display, assign a transform to its connector:

[output]
transforms = "HDMI-A-1:270"

Available tokens are normal, 0, none, 90, 180, 270, flipped, flipped-90, flipped-180, and flipped-270. Separate multiple connectors with semicolons:

[output]
transforms = "DP-1:normal; HDMI-A-1:90"

Transform is independent of the physical mode size and UI scale. Noctalia can also synchronize transforms; see Sync with Noctalia.

Scale the interface

When no layout or scale override applies, the greeter calculates each output’s scale from its physical dimensions reported by EDID, falling back to its resolution. It uses the selected DRM mode size so cold boot and post-logout results match. Automatic scale is capped at 2.

Scale is resolved independently for each output in this order:

1. Global [output].scale in greeter.toml
2. A connector entry in [output].scales from greeter.toml, then sync.toml
3. Scale 1.0 when [output].layout applies but the connector has no scale
4. Automatic scale from display geometry

Set different scales per connector:

[output]
scales = "DP-1:1; DP-2:1.25"

Or force one scale on every output:

[output]
scale = 1.5

An invalid global scale, including a non-positive number, is ignored and resolution continues with the next applicable step above. The greeter lays out its interface at logical size and renders HiDPI buffers with Wayland fractional scaling.

These settings affect only the greeter session. They do not configure scaling inside the desktop session, although Noctalia Sync can copy the desktop’s effective per-output scales to keep synchronized layouts valid.

Blank displays when idle

By default, the greeter never blanks the screen. To turn off active DRM outputs after a period without input, set [idle].timeout in seconds:

[idle]
timeout = 300

0 or an omitted key disables blanking. Valid values are 0 through 86400 (24 hours).

The greeter client keeps running while the outputs are blanked. A key press, mouse button press, or touch wakes them and restarts the idle timer. Pointer motion and scrolling wake an already blanked screen, but do not reset the timer while the screen is on. This prevents motion noise from a wireless mouse from keeping the greeter awake indefinitely.

NOCTALIA_GREETER_IDLE_TIMEOUT overrides the config value when set. Because greetd starts the greeter with an empty environment, add the variable to its session command with env:

[default_session]
command = "env NOCTALIA_GREETER_IDLE_TIMEOUT=300 /usr/bin/noctalia-greeter-session"

On NixOS with the nixpkgs module:

services.displayManager.noctalia-greeter.settings = {
  idle.timeout = 300;
};

With the project flake module instead:

programs.noctalia-greeter.settings = {
  idle.timeout = 300;
};

Both modules write the value to greeter.toml; neither adds the environment override to the greetd command. Restart greetd after changing the timeout as shown below.

Apply changes

Restart greetd after changing display settings:

sudo systemctl restart greetd

On runit:

sudo sv restart greetd