I installed the xfce-desktop package in order to give myself a lighter GUI to improve the performance of Kerbal Space Program -- and KSP now works great! However, since first logging into the XFCE Session or Xubuntu session, every time my screen locks (manual or timed) while logged into KDE Plasma I get an XFCE login, followed by a KDE login to unlock the screen. I'm also seeing the XFCE login screen when fresh starting the system, and I'd much rather have the KDE Plasma login.

If it matters, I'm on a Core2Duo, 8 GB RAM, nVidia GTx950 w/ 1 GB. Everything was working fine before installed XFCE, except (I was told) the load from KDE Plasma was affecting my game's performance.

$ sudo dpkg-reconfigure kdm
dpkg-query: package 'kdm' is not installed and no information is available
Use dpkg --info (= dpkg-deb --info) to examine archive files,
and dpkg --contents (= dpkg-deb --contents) to list their contents.
/usr/sbin/dpkg-reconfigure: kdm is not installed

I'm pretty sure I've had lightdm from installation of 14.04, rather than kdm -- and lightdm is still present (shows in task list).

How can I correct this?

  • Will try it when I get home. – Zeiss Ikon Feb 15 '17 at 17:06
  • @DavidFoerster Looks like kdm is MIA. I have a hunch reinstalling it will make xfce fail similarly... – Zeiss Ikon Feb 15 '17 at 22:16
  • I'm pretty sure I've always had lightdm rather than kdm. – Zeiss Ikon Feb 16 '17 at 12:05
  • I ran your command with lightdm subbed for kdm and got a return to command prompt without any message. Still have the duplicate screen unlock, can't tell yet if other issues were improved. – Zeiss Ikon Feb 16 '17 at 12:15
  • Let us continue this discussion in chat. – Zeiss Ikon Feb 16 '17 at 12:21

It turned out that for some reason KDM was removed. To reinstall it:

sudo apt install kdm

If KDM is installed but disabled in favour of a different display manager, e. g. LightDM, you can reconfigure KDM as the default again:

sudo dpkg-reconfigure kdm

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