F34 Change proposal: Wayland by Default for KDE Plasma Desktop (System-Wide Change)

[Ben Cotton]

https://fedoraproject.org/wiki/Changes/WaylandByDefaultForPlasma

== Summary ==
Change the default session selection in SDDM to prefer the
Wayland-based KDE Plasma Desktop session over the X11-based one.

== Owner ==
* Name: [[User:Ngompa|Neal Gompa]], [[User:Rdieter|Rex Dieter]],
[[User:Jgrulich|Jan Grulich]]
* Email: ngompa13(a)gmail.com, rdieter(a)gmail.com, jgrulich(a)redhat.com
* Product: KDE Spin
* Responsible WG: KDE SIG


== Detailed Description ==

With KDE Plasma 5.20, the KDE Plasma desktop environment has reached a
point where nearly all commonly used features in the desktop and all
major applications function in the Plasma Wayland environment on all
major GPUs (including NVIDIA with the proprietary driver). Starting
with Plasma 5.20 in Fedora 34, we will change the default
configuration for Wayland and X11 Plasma sessions so that Wayland is
preferred and used by default, while permitting the X11 session to be
selected as the alternative desktop environment option.

== Feedback ==

==== Is Wayland ready? ====
Wayland has been used by default for Fedora Workstation (which uses
GNOME) since Fedora 25. And while it was somewhat immature initially,
today it is a very rock-solid experience on virtually everything
Fedora Workstation runs on. The change in Fedora 25 kickstarted the
drive to get everything working on Wayland, and the Workstation team
succeeded beyond their wildest dreams. Firefox has been Wayland-native
by default since Fedora 31 as well.

On the KDE side, serious work into supporting Wayland started shortly
after GNOME switched to Wayland by default. Unlike GNOME, KDE has a
much broader stack in its toolkit, and it has taken longer to get to a
usable state. With the Plasma 5.20 release, the Wayland protocol for
screencasting as well as middle-click paste finally are supported,
completing the required feature set for switching to Wayland by
default.

==== What about NVIDIA? ====
Plasma, in fact, ''does'' support NVIDIA GPUs with the proprietary
driver on Wayland. It needs to be manually activated, which will be
taken care of by the <code>kwin-wayland-nvidia</code> package. So the
expectation is that all major GPUs will work just fine.

==== Why not keep using X11? ====
The fact of the matter is, Xorg is in
[https://blogs.gnome.org/uraeus/2019/06/24/on-the-road-to-fedora-workstati...
"hard maintenance mode"] per [[User:Uraeus|Christian Schaller]] and
development on it has basically stopped beyond the most critical of
fixes. Combined with the rapid maturation of the Wayland session in
KDE Plasma, this is the best time to make the switch and push things
over the edge for the KDE ecosystem in the same way that Fedora
Workstation did for the GNOME ecosystem.

== Benefit to Fedora ==
Fedora has long been a leader in advancing the adoption of the Wayland
protocol as part of the overall strategy to improve the Linux
graphical software stack. Much of the quality of Wayland for GNOME can
be attributed to the work done by the Fedora Workstation WG as part of
advancing the GNOME platform. It is now the KDE SIG's turn to do the
same for the KDE platform. By making this change, we are helping push
the adoption forward for newer, more streamlined, and overall more
actively developed graphics technology for the KDE ecosystem.

== Scope ==
* Proposal owners:
** Modify {{package|kwin}} to switch to Wayland
*** Split out <code>/usr/bin/kwin_x11</code> to the
<code>kwin-x11</code> subpackage.
*** Make {{package|kwin}} require <code>kwin-wayland</code> and
recommend <code>kwin-x11</code>
*** Add <code>kwin-wayland-nvidia</code> subpackage which contains
<code>/usr/lib/environment.d/10-kwin-wayland-nvidia.conf</code> to set
<code>$KWIN_DRM_USE_EGL_STREAMS</code> to <code>1</code>. This
package
will have have a Supplements dependency <code>(kwin-wayland and
kmod-nvidia)</code>.
** Modify {{package|plasma-workspace}} to switch to Wayland
*** Rename <code>/usr/share/xsessions/plasma.desktop</code> to
<code>/usr/share/xsessions/plasma-xorg.desktop</code>, subpackage it
out as <code>plasma-workspace-xorg</code>, and have it require
<code>kwin-x11</code>
*** Rename <code>/usr/share/wayland-sessions/plasmawayland.desktop</code>
to <code>/usr/share/wayland-sessions/plasma.desktop</code>
*** Make {{package|plasma-workspace}} require
<code>plasma-workspace-wayland</code> and recommend
<code>plasma-workspace-xorg</code>
** Modify <code>@kde-desktop</code> comps group for Fedora 34 to
include <code>plasma-workspace-xorg</code> for the media.

* Other developers: N/A (not applicable for this Change)
* Release engineering: [https://pagure.io/releng/issue/9741 #9741]
* Policies and guidelines: N/A (not needed for this Change)
* Trademark approval: N/A (not needed for this Change)
* Alignment with Objectives: N/A (not applicable for this Change)

== Upgrade/compatibility impact ==
Systems using certain (very old) graphics hardware or graphics drivers
(matrox, etc.) may have problems running the Wayland session. In these
(rare) cases, users may have to configure SDDM to use X11.

== How To Test ==
Log into a KDE Plasma desktop. Do any activity you would normally do
in your daily desktop use: launching applications, configuring
displays, etc. Things should work the same way under Wayland as they
used to under X.

== User Experience ==
The user experience should not change noticeably.

== Dependencies ==
This mainly affects the {{package|plasma-workspace}} and
{{package|kwin}} packages, and details for the changes for those
packages are described in the Scope section.

== Contingency Plan ==
* Contingency mechanism: Revert the file renames and switch
<code>plasma-workspace-xorg</code> to be the required package instead
of <code>plasma-workspace-wayland</code>
* Contingency deadline: beta freeze
* Blocks release? Yes
* Blocks product? KDE Spin

== Documentation ==
Some upstream documents about Wayland
* https://community.kde.org/Plasma/Wayland
* https://community.kde.org/KWin/Wayland

There is currently no coherent up to date documentation about Plasma Wayland.

== Release Notes ==
The KDE Plasma Desktop is using the Wayland display system now. X
applications will continue to run transparently through XWayland.


-- 
Ben Cotton
He / Him / His
Senior Program Manager, Fedora & CentOS Stream
Red Hat
TZ=America/Indiana/Indianapolis