SDDM

Resources

Simple Desktop Display Manager (SDDM) is a modern display manager that supports both the X11 server and the Wayland protocol.

Installation

USE flags

USE flags for x11-misc/sddm Simple Desktop Display Manager

`elogind`	Use sys-auth/elogind for session tracking.
`pam`	Add support for PAM (Pluggable Authentication Modules)DANGEROUS to arbitrarily flip
`systemd`	Enable use of systemd-specific libraries and features like socket activation or session tracking
`test`	Enable dependencies and/or preparations necessary to run tests (usually controlled by FEATURES=test but can be toggled independently)

Data provided by the Gentoo Package Database · Last update: 2020-10-10 10:13 More information about USE flags

Emerge

Install x11-misc/sddm:

root #emerge --ask x11-misc/sddm

If there are performance issues, it might help to add the sddm user to the video group:

root #usermod -a -G video sddm

Configuration

Files

SDDM has two configuration files: the package installed /usr/share/sddm/sddm.conf.d/00default.conf and /etc/sddm.conf which is used to override specific options. The second is not created by the package. KDE Plasma writes user changed options to /etc/sddm.conf. Both files have the same format. See comments in the file and man 5 sddm.conf for details on available options.

Prior to 0.18.0

Prior to 0.18.0 the configuration was only in /etc/sddm.conf. Some of the files may have had to be generated manually. If installing 0.18.0, skip ahead to Service section.

Keymap

To select the correct keymap on the login screen, add following lines to the /etc/sddm.conf file:

FILE /etc/sddm.conf

[X11]
DisplayCommand=/etc/sddm/scripts/Xsetup

This file is not created automatically when the package is installed so you'll need to create it if you haven't done so already.

Next create the directory /etc/sddm/scripts

root #mkdir -p /etc/sddm/scripts

and the file /etc/sddm/scripts/Xsetup.

FILE /etc/sddm/scripts/Xsetup

setxkbmap gb,us

the first country code is the default. Finally set execute permissions on the file /etc/sddm/scripts/Xsetup.

root #chmod a+x /etc/sddm/scripts/Xsetup

Service

OpenRC

Set SDDM as the default display manager:

FILE /etc/conf.d/xdm

DISPLAYMANAGER="sddm"

To start SDDM on boot, add xdm to the default runlevel:

Note
The dbus service gets pulled in dynamically.

root #rc-update add xdm default

To start SDDM now:

root #/etc/init.d/xdm start

systemd

To start SDDM on boot:

root #systemctl enable sddm.service

To start SDDM now:

root #systemctl start sddm.service

Plasma

Graphical configuration is integrated in Plasma 5 system settings by installing kde-plasma/sddm-kcm:

root #emerge --ask kde-plasma/sddm-kcm

Troubleshooting

Long load time before SDDM shows the greeter

A low entropy pool can cause long SDDM load time - see upstream bug report. If using systemd, the graphical target is reached and then everything appears to hang. Moving the mouse or using the keyboard will make the SDDM greeter launch (faster).

Solve the problem by using, for example, the sys-apps/haveged package to increase the entropy pool or by enabling RANDOM_TRUST_CPU kernel config option with a recent-enough CPU.

Permission denied errors in Xorg.log

The X server will not start and permission denied errors (such as the following) are present in the Xorg.log log file:

FILE /var/log/Xorg.log

/var/log/Xorg.0.log:[ 2058.998] (EE) /dev/dri/card0: failed to set DRM interface version 1.4: Permission denied
/var/log/Xorg.0.log:[ 2061.229] (EE) intel(0): [drm] failed to set drm interface version: Permission denied [13].

It is likely the sddm user has not been added to the video group. Running the following command should fix the problem:

root #usermod -a -G video sddm

Missing users

If the login screen is missing some user(s) to choose from, this might be caused by /etc/sddm.conf - standard MinimumUid is 1000 and some existing users may have lower uids.

FILE /etc/sddm.conf

[Users]
MaximumUid=60000
MinimumUid=1000

SDDM service starts but yields a black screen

On NVIDIA cards, SDDM appears to require DRM enabled and operational according to this closed bug report.

Ensure Direct Rendering Manager is enabled in the kernel. If it isn't, enable it, rebuild the kernel, and re-emerge nvidia-drivers.

KERNEL Enable Direct Rendering Manager

Device Drivers --->
    Graphics support --->
        <*> Direct Rendering Manager (XFree86 4.1.0 and higher DRI support) --->
            [*] Enable legacy fbdev support for your modesetting driver

Ensure the nvidia-drm module is configured to load at startup:

FILE /etc/modules-load.d/nvidia-drm.conf

nvidia-drm

Finally, ensure nvidia-drm has modesetting enabled:

FILE /etc/modprobe.d/nvidia-drm.conf

options nvidia-drm modeset=1

Alternatively, modesetting can be enabled on the kernel command line with nvidia-drm.modeset=1. This can be set in the bootloader or embedded in the kernel configuration.