Changes/WaylandByDefaultForSDDM

Wayland by Default for SDDM

Summary

Change the default display server mode for SDDM to use a Wayland-based greeter rather than an X11-based one.

Owner

• Name: Neal Gompa, Rex Dieter, Jan Grulich
• Email: ngompa13@gmail.com, rdieter@gmail.com, jgrulich@redhat.com
• Product: KDE Spin, Kinoite
• Responsible WG: KDE SIG

Current status

• Targeted release: Fedora Linux 38
• Last updated: 2022-08-22
• devel thread
• FESCo issue: #2740
• Tracker bug: #2050378
• Release notes tracker: #800

Detailed Description

With the work done upstream in SDDM to support using a Wayland based greeter and the introduction of SimpleDRM to fix the broken fallback when platform drivers are unavailable, it is now possible for the Fedora KDE variants (the regular spin and Kinoite) to move to Wayland for the login manager, which effectively completes the switch to Wayland for these variants.

Benefit to Fedora

As originally detailed in the Change to switch Plasma to Wayland by default, Fedora is a leader in advancing the adoption of the Wayland protocol as part of the overall strategy to improve the Linux graphical software stack. We have been successful in helping drive Wayland forward in the Plasma Desktop, and we intend to do the same for SDDM.

Scope

• Proposal owners:
  • Upgrade sddm to the latest snapshot and introduce mutually exclusive sddm-wayland-generic and sddm-x11 greeter configuration packages.
  • Modify plasma-workspace to switch SDDM to Wayland
    • Enable installation of the SDDM Wayland configuration snippet and ship as sddm-wayland-plasma that is mutually exclusive with the other sddm greeter configuration packages. This package will supplement sddm and plasma-workspace-wayland to be automatically installed together.
  • Modify @kde-desktop comps group for Fedora Linux 36 to include sddm-wayland-plasma for the media.

• Other developers: N/A (not needed for this Change)

• Release engineering: #10536

• Policies and guidelines: N/A (not needed for this Change)

• Trademark approval: N/A (not needed for this Change)

• Alignment with Objectives: N/A

Upgrade/compatibility impact

On upgrade to Fedora Linux 36, SDDM will be transparently switched from the X11 greeter to the Wayland one leveraging kwin. In order to override this, the user can do one of the following:

• Drop in a configuration file in /etc/sddm.conf.d to set the display server back to X11
• Swap back to X11 with the configuration package: dnf swap sddm-wayland-plasma sddm-x11

How To Test

Once the SDDM and Plasma Wayland changes are made, Rawhide users can try this by using nightly KDE ISOs and using them normally to install and run a Rawhide KDE Plasma environment.

See the configuration files for:

• Force X11: https://src.fedoraproject.org/rpms/sddm/blob/rawhide/f/sddm-x11.conf
• Force Wayland: https://src.fedoraproject.org/rpms/sddm/blob/rawhide/f/sddm.conf#_27

User Experience

Ideally, there should be no noticeable impact on the user experience, though users may notice that things operate more smoothly and with slightly lower resources.

Dependencies

This change is dependent on the Change to replace fbdev with SimpleDRM. Without that Change, we will need to keep SDDM using X11 because otherwise the fallbacks are broken when drivers do not work.

Contingency Plan

• Contingency mechanism: Update comps and plasma-workspace so that sddm-x11 is shipped instead.
• Contingency deadline: beta freeze
• Blocks release? Yes

Documentation

N/A (not a System Wide Change)

Release Notes

SDDM, the login manager for the Fedora variants using the KDE Plasma Desktop, now uses the Wayland display system.