As an ancient conceit, when processes stop, all their children are supposed to orderly exit too (note: There are a few exceptions perhaps), but that’s the base of it. Children don’t outlive their parents.
2 Likes
Please bear with me if this is a bit technical. I was under the impression that in Linux using C/C++ one can do a fork() - exec() pattern to separate or spin off the child process.
So for example the display manager, i.e. SDDM/GDM/LightDM/etc, spawn the DE, in this KDE, using fork, and then immediately do a exec on it.
From the blog
Off course when the DE, in this case KDE, exits it will have to transfer control to the display manager.
1 Like
Yep, that’s possible, but as I said, it’s typical to clean up all spawned processes when you exit. That’s the default model.
1 Like
Got my KDE - Plasma by running pacman -Syu. I did sudo pacman -S plasma-login-manager
sudo systemctl disable sddm
sudo systemctl enable plasmalogin
sudo pacman -R sddm-kcm
sudo pacman -R eos-breeze-sddm
sudo pacman -R sddm
and I login perfectly with Lightdm.
I did
sudo systemctl -f enable plasmalogin
ans still I have my login perfectly with Lightdm.
whats causes no trouble but wonder why
As @shadow359 posted earlier in this thread, this worked perfectly for me…
sudo pacman -S plasma-login-manager
sudo systemctl disable sddm
sudo systemctl enable plasmalogin
sudo pacman -R sddm-kcm
sudo pacman -R eos-breeze-sddm
sudo pacman -R sddm
I see that you disabled SDDM, but I don’t see where you disabled LightDM.
2 Likes
To summarise:
1- There is no need to uninstall sddm. In fact, it is better to leave it installed in case there are any problems.
2- To activate Plasma Login Manager:
Install it if you do not have it:
sudo pacman -S plasma-login-manager
Then:
sudo systemctl disable sddm
sudo systemctl enable plasmalogin
or
sudo systemctl -f enable plasmalogin
3- To return to sddm:
sudo systemctl disable plasmalogin
sudo systemctl enable sddm
or
sudo systemctl -f enable sddm
4- To check which manager is active:
systemctl status display-manager
and/or
ls -l /etc/systemd/system/display-manager.service
5- To check which ones we have installed:
pacman -Qs "sddm|gdm|lightdm|plasma-login-manager"
Cheers.
7 Likes
You are absolutely right, I thought the last enabeling would set my Desktop manager on the top automaticaly…
I updated to KDE Plasma 6.6 and installed the Plasma Login Manager as well as purged the SDDM no issues so far…
Running Wayland BTW(for like 2+ years now).
4 Likes
Reinstalled plasma-login manager and logged in with wayland instead of xorg. It’s all fine now.
2 Likes
A little side-note to this, SDDM was largely on life-support and kept going by the KDE Plasma maintainers. Development has now switched to PLM. It’s a great idea to have a backup login manager, but I’d be inclined to choose one that’s actively maintained. SDDM will be (unless someone chooses to maintain it instead of forking as KDE have done) largely deprecated and liable to incur potential bugs over time as Plasma changes.
7 Likes
seems we now have 2 threads about the same thing 
is there so may read there and ask the questions about PLM
not as a general way to use the Desktop.. its to play/tinker ionly some tips to0 make your life easier with this. and yea i had the info in () that it will end the Desktop session
On arch in general.. no GUI 
does not say the OS is broken in any way in most cases everything under the hood still running for your service.
2 Likes
Switched to PLM? What is PLM?
It would be sad that SDDM is no longer maintained or is deprecated. If KDE developers/maintainers were to make an effort then SDDM ought to be the logically choice. Let us not forget what happened to the KDE, i.e. KDE Display manager.
Plasma Login Manager, it is a fork of SDDM
SDDM hasn’t been properly maintained in quite some time, the KDE devs have been mostly keeping it alive even though it isn’t a KDE project. That is why they are investing in PLM.
thank you. works like a charm 
1 Like