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Revision as of 23:07, 7 September 2017 by Tterranigma (talk | contribs) (Adds the only thing that has worked for me in having decent resolution with sddm)
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The Simple Desktop Display Manager (SDDM) is the preferred display manager for KDE Plasma desktop. From Wikipedia:

Simple Desktop Display Manager (SDDM) is a display manager (a graphical login program) for X11. SDDM was written from scratch in C++11 and supports theming via QML. It is the successor of the KDE Display Manager and is used in conjunction with KDE Frameworks 5, KDE Plasma 5 and KDE Applications 5.


Install the sddm package.

Then follow Display manager#Loading the display manager to start SDDM at boot.


The configuration file for SDDM can be found at /etc/sddm.conf. See sddm.conf(5) for all options.

On systems controlled by systemd, everything should work out of the box, since SDDM defaults to using systemd-logind for session management. The configuration file will therefore not be created at package installation time. SDDM offers a command for generating a sample configuration file with the default settings if you really want one:

# sddm --example-config > /etc/sddm.conf


SDDM supports automatic login through its configuration file, for example:


This configuration causes a KDE Plasma session to be started for user john when the system is booted. Available session types can be found in /usr/share/xsessions/ directory.

An option to autologin into KDE Plasma while simultaneously locking the session is not available [1]

You can add a script that activates the screensaver of KDE to the autostart as a workaround:

/usr/bin/qdbus-qt4 org.kde.screensaver /ScreenSaver SetActive true &
exit 0

Unlock KDE Wallet automatically on login

See KDE Wallet#Unlock KDE Wallet automatically on login.

Theme settings

Theme settings can be changed in the [Theme] section.

Set to breeze for the default Plasma theme.

Some themes are available in the AUR, for example archlinux-themes-sddmAUR.

Current theme

Set the current theme through the Current value, e.g. Current=archlinux-simplyblack.

Editing themes

The default SDDM theme directory is /usr/share/sddm/themes/. You can add your custom made themes to that directory under a separate subdirectory. Note that SDDM requires these subdirectory names to be the same as the theme names. Study the files installed to modify or create your own theme.

Mouse cursor

To set the mouse cursor theme, set CursorTheme to your preferred cursor theme.

Valid Plasma mouse cursor theme names are breeze_cursors, Breeze_Snow and breeze-dark.

Changing your avatar

You can simply put a png image named username.face.icon into the default directory /usr/share/sddm/faces/. Alternatively you can change the default directory to match your desires:


You can also put a png image named .face.icon at the root of your home directory. However, you need to make sure that sddm user can read that file.

Note: If avatar images are symlinks, you need to set proper file permissions to the target files.


If you want to enforce Numlock to be enabled, set Numlock=on in the [General] section.

Rotate display

See Xrandr#Configuration.

Configuration GUI

  • KDE Frameworks' System Settings contains an SDDM configuration module. Install sddm-kcm package to use it.
  • There is a Qt-based sddm-config-editor-gitAUR in the AUR.

DPI settings

Sometimes it's useful to set up correct monitor's PPI settings on a "Display Manager" level. To do so you need to find "ServerArguments" parameter in sddm.conf and add -dpi %YOUR RESOLUTION at the end of the string.

For example:

ServerArguments=-nolisten tcp -dpi 94

SDDM and Gnome-keyring

To automatically unlock the Gnome-keyring upon login in KDM add the following line to your /etc/pam.d/sddm right after the auth include system-login line:

auth            optional

and add

session         optional auto_start

after session include system-login

To automatically re-unlock the keyring when you unlock your screensaver open /etc/pam.d/kscreensaver and add

auth            optional

as the last line.


Hangs after login

Try removing ~/.Xauthority.

SDDM starts on tty1 instead of tty7

SDDM follows the systemd convention of starting the first graphical session on tty1. If you prefer the old convention where tty1 through tty6 are reserved for text consoles, uncomment and edit the MinimumVT variable, under the [X11] section in sddm.conf:


One or more users do not show up on the greeter

Warning: Users set with a lower or higher UID range should generally not be exposed to a Display manager.

SDDM only displays users with a UID in the range of 1000 to 65000 by default, if the UIDs of the desired users are below this value then you will have to modify this range. Modify your sddm.conf to (for a UID of 501, say):

# Hidden users, this is if any system users fall within your range, see /etc/passwd on your system.

# Maximum user id for displayed users

# Minimum user id for displayed users
MinimumUid=500 #My UID is 501

SDDM loads only US keyboard layout

SDDM loads the keyboard layout specified in /etc/X11/xorg.conf.d/00-keyboard.conf. You can generate this configuration file by localectl set-x11-keymap command. See Keyboard configuration in Xorg for more information.

No user Icon

SDDM reads user icon from either ~/.face.icon or FacesDir/username.face.icon

You need to make sure that SDDM user have permissions to read those files.

$ setfacl -m u:sddm:x /home/username
$ setfacl -m u:sddm:r /home/username/.face.icon

See SDDM README: No User Icon.

Screen resolution is too low

Issue may be caused by HiDPI usage for monitors with corrupted EDID: [2]

Try disabling HiDPI in sddm.conf:

# Enable Qt's automatic high-DPI scaling

If even the above fails, you can try setting your screen size in a Xorg conf file:

Section "Monitor"
        Identifier      "<default monitor>"
        DisplaySize     345 194 # in millimeters