[SOLVED]How to completely migrate to Wayland w/o starting X?

nagmat84 · Apprentice Joined: 27 Mar 2007 Posts: 262

With the advent of KDE 6 I thought it has been time to start experimenting with Wayland. I am running a pure KDE enviroment with SDDM as the display manager.

I can start X (X.org) which in turn starts SDDM which gives me an option to either start KDE on X11 or as a Wayland session. However, I am wondering how a full migration to Wayland would look like (even if it might not be the right time yet and a task for the far future). I understand that with Wayland, there is no dedicated display server like X, but KWin takes over the role of an integrated Wayland server and compositor. There are basically two question spinning around in my head:

Question 1: How to start SDDM as a login screen on top of KWin without Xorg?

Currently, first the X server is started which then starts SDDM and after a successful login SDDM starts KWin on top of the X server. When X will be totally gone, how do I tell SDDM that it should run on top of KWin? Or do I have to start KWin which then starts SDDM? Which systemd service units need to be changed in what way?

Currently. /usr/lib/systemd/system/sddm.service is installed and enabled as /etc/systemd/system/display-manager.service.

Question 2: How to migrate system-wide graphical default settings from X.org to Wayland (or KWin for that matter)?

Currently, I have a couple of drop-in configuration files for X.org which set the default monitor resolution, pixel density, monitor arrangement and keyboard layout. In particular, monitor arrangement and pixel density are important so that office and graphic programs correctly scale 100% paper width according to the actual physical size. However, these configuration files are specific for X.org. What is their Wayland/Kwin replacement?

rab0171610 · Guru Joined: 24 Dec 2022 Posts: 423

nagmat84 · Apprentice Joined: 27 Mar 2007 Posts: 262

Your post doesn't answer the question. Your post repeats the status quo which I am aware of and which you could know if you had read my post carefully.

The question specifically addressed the question how the situation is supposed to be in the future (maybe even far future) and what the long-term solution is supposed to look like after X will have been gone.

The entire idea of Wayland is to get rid of X one day. I know that we are not there yet and that the current default is to still run SDDM on X and then log into a Wayland session. But that wasn't the question.

There are more or less four possible answers to my question:

a) There is simply no plan yet. Nobody has ever spent a thought on how to login in a Wayland-based desktop session without running a screen manager like SDDM on X first. We will still need X for decades to come for the login process. (I hope this option is not the answer).

b) There have been some preliminary ideas on how the login process could run on Wayland, but nothing has really been settled nor implemented yet.

c) There is on-going, active, upstream development and it already runs in some kind of alpha-state, but it is not yet packaged into Gentoo. However, the principle road ahead is clear.

d) There is an solution which is considered ready for productive use from the upstream perspective and it is included in testing stage in Gentoo. If one is adventurous and wants to give it a try, the following steps needs to be followed.

pietinger · Posted: Sat Aug 17, 2024 2:53 pm Post subject:

nagmat84,

the answer is:

e) It depends ...

Goverp · Advocate Joined: 07 Mar 2007 Posts: 2179

The answer to Q1 is that this is a pointless question. Why should SDDM run on Kwin? SDDM runs before the end user is logged in, and therefore runs under its own userid in its own process, completely separate from the eventual end-user KDE process. What, if any, screen driver it uses is up to the SDDM developers. That might point them in the KDE direction, but arguably having SDDM require starting its own copy of part of the Qt and KDE stack just to ask you to type in a password on a pretty screen is perhaps a bit overkill. You could consider one of the several other display managers (most of which in my view are pretty ugly, and that includes SDDM.)

FWIW, and I guess that's nothing, I don't bother with SDDM. I use a getty screen and reply to the, admittedly less than pretty, default Linux login userid and password prompt, and one of my profile scripts (off hand I forget which) runs a programs to start (in my case) either a simple command shell, KDE using Wayland or KDE using X, depending on which tty. That way I can select the session I get easily, and I can at the moment still fall back to X if Wayland gets particularly annoying.

I use Wayland virtually all the time. The main gripes are:
a) Every so often the KDE desktop vanishes, though open windows remain, and Alt F2 gets a command line (to enter Logoff usually) and moving the mouse to the TLH corner of the screen gets me a choice of windows.
b) Zoom won't let me share my screen properly - I been told this is fixable more than once, but as it's so minor I still haven't fixed it.

I'm not sure why you're even asking Q1 here. It's one for the SDDM devs. This is Gentoo...

Q2, I suspect with a post-it note and careful use of the KDE System Settings application, but I wouldn't know, as I just let X do its default thing and everything works for my very simple setup. Certainly monitor arrangement and resolution is covered in KDE "Configure Display Settings" (at least as much as I need, e.g. when plugging in an external monitor on my laptop) which is part of System Settings.
_________________
Greybeard

rab0171610 · Guru Joined: 24 Dec 2022 Posts: 423

I am sorry you feel that your post was not read "carefully enough."

nagmat84 · Apprentice Joined: 27 Mar 2007 Posts: 262

I did it. SDDM now also uses KWin as the display server and (Wayland) compositor. Wayland support for SDDM is considered experimental. However, on my desktop PC with an AMD GPU and my laptop with an Intel GPU it works without any noticeable problem. I even believe that the new setup is faster and smoother than before. (Maybe because SDDM does not start an X11 server first and when I log in KWin is already running.)

I followed the guides at

The latter also contains the instructions I was looking for. KWin stores the monitor layout in the file "kwinoutputconfig.json". This file must reside in the ".config" dir of the user who is running KWin. The easiest way to create that file is to log in as a user, set the monitor layout as desired and then copy that file from the user to the correct location within the home directory of the user sddm which runs KWin for SDDM.

/etc/sddm.conf.d/02-wayland.conf