How to change monitor layout and orientation in SDDM?

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1

I’ve never attempted this before, so I’m not sure how flexible SDDM is, and I’m a noob with xrandr.

I have a 4K+1440p monitor setup (in that order), with the 1440p being the primary (will replace with 1440p ultrawide).

  • I want to rotate the 4K monitor 90° CW only
  • I want 1440p to be the primary monitor
  • (Optional) I want to put a different wallpaper on my portrait display

How can I accomplish that? And if I were to swap one of the monitors or move the cables around, it won’t crash SDDM or cause issues?

2

Edit these 2 files, if not exist create them. Note that DP-2 and DP-4 are examples. Find out which port your monitor connecting to by running xrandr. If rotate right is not right then change to left.

/usr/share/sddm/scripts/Xsetup

xrandr --output DP-2 --mode 3840x2160 --rotate right --auto --noprimary --output DP-4 --mode 2560x1440 --rotate normal --auto --primary

When you change to 2k Ultrawide

xrandr --output DP-2 --mode 3840x2160 --rotate right --auto --noprimary --output DP-4 --mode 3440x1440 --rotate normal --auto --primary

/etc/sddm.conf

[XDisplay]
# Xsetup script path
# A script to execute when starting the display server
DisplayCommand=/usr/share/sddm/scripts/Xsetup

For wallpaper open settings and search SDDM.

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3

Thanks for that
And regarding the wallpaper, I edited my post

4

This is supported out of the box if you use Wayland. Then go to the SDDM page in System Settings and click the “Apply Plasma Settings” button.

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5

Nice Nate! That’s actually something I mentioned would be nice in a Github bug. I didn’t know it had already been implemented.

6

Out of curiosity, what happens if I need to change back to my “regular” 1440p? Will it break? Or how will SDDM handle that situation (mainly for curiosity sake).

oh that’s good to hear. I just hope that Wayland will be ready for gaming soon

7

On Wayland, SDDM it remembers resolutions per-screen, so that shouldn’t be a problem.

But it’s a manual process, so every time you change a screen’s resolution, you’ll need to re-sync the SDDM settings if you want them to remain in sync.

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8

Any plans on making it automatic in the future?

9

Once SDDM is brought into KDE, it might be possible to make it automatic, as long as you have only one user of course. If you have multiple users, it would either have to be manual again, or track only a single user’s configurations.

10

What about last-one’s config is the default until user changes?

11

Could be, but this would cause the SDDM setup to change dynamically based on past state. People are bad at remembering past state, and often don’t know it at all, in the case of a genuine multi-user system where each account belongs to a different person. It could end up feeling very magical and unpredictable.

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12

what about an additional prompt after applying, saying “would you like this applied as default (requires Administrator access)”?

For cases of when its being used as thin client, the user can open a ticket to have it applied by default.

Or another case can be a toggle that says anyone can change the screen layout (in cases of corporate laptops), but requires Administrator to apply that.

13

Yes, but it would change the config based on the last user.

Some user would need fractional scaling, others don’t.

In my last job, I used to use a laptop with a higher resolution that belonged to a coworker (my work laptop broke at the time). I disabled fractional scaling and used the full 2560x1600 resolution at 100%, but when she received it back, the laptop switched back to 1920x1200 (didn’t want to use fractional scaling due to a core app not working right), and switched back to 2560x1600 when I’m the one logging in.

So essentially, it can work if it retains the last used state, and will switch to a logged in user’s preferred state.

14

it doesn’t work on Plasma 6…
I have 2 issues, the first is the hidpi settings that I had to set manually in a conf file, and the second is the monitor orientation. I clicked on Apply Plasma settings but it doesn’t seem to do anything.

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15

Ok, now I see why it did not work for me. Plasma 6…
I hope it will be fixed any time soon.

In addition, I see the wrong cursor.

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16

Can confirm, I’ve experienced this issue as well.

SDDM settings don’t really take using the GUI button, and even if they do, they will not work when you log out, and the screen orientation will be reset.

17

Strange. I’m using Tuxedo OS 3 (22.04/Plasma 6) on my ThinkPad, and it seems to be working.

External monitor is LG DualUP in picture-by-picture mode, and SDDM recognized the layout (2x 1440p DualUp on the left, and primary 1080p laptop on the right). Even layout is kept.

Didn’t try rotation as I’m not using a rotated monitor anymore.

18

Applying the settings either through the UI or copying the file as described in the Arch wiki page for SDDM (2.12.1.2 Match Plasma display configuration) also does not work for me (on a brand new Arch install).

19

For anyone still struggling with this, the trick is you need to identify your monitors while you are logged into an X11 session. The output of xrandr will not be the same for a Wayland session.

For me, under Wayland, my monitors were DP-1 and DP-2. Under X11, they are DisplayPort-0 and DisplayPort-1. You must identify them with the X11 name for SDDM.

For my setup:
/usr/share/sddm/scripts/Xsetup

#!/bin/bash
# Xsetup - run as root before the login dialog appears
xrandr --output DisplayPort-1 --off
20

I agree it doesn;t work on Plasma 6. I have a bug open on this, although i’m sure mine will not be the first.