KDM to SDDM

English Install/Boot/Login
1

I decided to switch from KDM to SDDM after installing Plasma 5 and would like some help. Following the Arch Wiki, I installed SDDM and uninstalled KDM, then ran

sudo systemctl disable kdm && systemctl enable sddm

The problem is, this is the result.

Failed to execute operation: No such file or directory

And running sddm --test-mode results in


[16:42:34.866] (II) DAEMON: Initializing...
[16:42:34.873] (II) DAEMON: Starting...
[16:42:34.873] (II) DAEMON: Adding new display 1 on vt 1 ...
[16:42:34.874] (II) DAEMON: Adding cookie to "./:1"
[16:42:34.879] (WW) DAEMON: Failed to change owner of the auth file.
[16:42:34.879] (II) DAEMON: Display server starting...
[16:42:34.880] (EE) DAEMON: Failed to start display server process.

I would like to ask where I am going wrong. Am I missing something obvious or forgot about a certain step? Is it even worth it to change from KDM to SDDM currently?

By the way, I am using openSUSE Tumbleweed. If you would need any other information, I would happily give it to you. Any help is gladly appreciated.

2

Edit /etc/sysconfig/displaymanager and replace kdm in the DISPLAYMANAGER="" with sddm and **systemctl restart display-manager.service

**This being a completely uneducated guess and how I’ve always done it when I’ve been testing some unorthodox dm’s.

3

Worked absolutely perfectly! Thanks a lot!

4

That is correct, yes.
Currently, all displaymanagers are started via the xdm startup script according to the settings in /etc/sysconfig/displaymanager.

This only applies if you installed the openSUSE sddm package though, of course.

You don’t have to uninstall KDM. You can have as many displaymanagers installed as you want. Just set your preferred one in /etc/sysconfig/displaymanager.

And don’t follow the Arch Wiki, that does not apply at all to openSUSE in this case.

Is it even worth it to change from KDM to SDDM currently?

That depends on your needs.
SDDM should work fine, and it even has a Plasma5 config module.
But it still lacks a lot of features compared to KDM e.g., like XDMCP/VNC/RDP/remote login or remembering the last used session per user. See also their TODO list: TODO · sddm/sddm Wiki · GitHub

In the end you have to decide yourself if you are satisfied with SDDM already.

And there is an issue that will prevent you from logging out correctly: pam_gnome_keyring.so freezes session logout · Issue #286 · sddm/sddm · GitHub
A workaround for this would be to uninstall gnome-keyring-pam.

5

Interesting, thank you.

I like to follow the openSUSE wiki but that doesn’t even have an article on SDDM so I had to make an exception.

Thank you for the information, I’ll keep it in mind and decide.