1:05 p.m.
https://fedoraproject.org/wiki/Changes/XwaylandStandalone
== Summary ==
Move Xwayland to a standalone package built from current code upstream
rather than the stable branch.
== Owner ==
* Name: [[User:ofourdan| Olivier Fourdan]], [[User:mdaenzer| Michel Dänzer]]
* Email: <ofourdan(a)redhat.com>, <mdaenzer(a)redhat.com>
== Detailed Description ==
Xorg releases upstream are stuck to the current 1.20 branch for years
with no foreseeable future major update.
But Xwayland, the X11 server for Wayland, is receiving quite a lot of
updates upstream.
Xwayland has no device dependent driver loaded at run time, doesn't
load any module, so it is not limited by the Xorg API versioning like
the rest of Xorg.
So technically, there is nothing stopping us from having Xwayland as a
standalone separate package built on git master, while the rest of
xorg-x11-server comes from the stable tree upstream.
This change is about moving Xwayland to a separate package from the
rest of Xorg, built from git snapshots of the current code upstream
rather than the stable branch.
== Benefit to Fedora ==
Xwayland from upstream current code has interesting features missing
from the stable branch, some are backported manually in the current
Fedora package, but some others aren't.
There are also existing COPRs trying to backport those features, but
that can introduce bugs. Using the code from upstream would avoid the
appeal or even the need for such backports.
===XRandR emulation for games===
Those changes from [[User:Jwrdegoede | Hans De Goede]] are already
backported in the current Fedora package for each new release, using
Xwayland from current code upstream would save us from this backport
process, and the potential issues induced by backports.
===Multiple window buffers===
This is basically "tearfree" for Xwayland applications.
===initfd support===
To be able to run Xwayland on demand, the compositor needs a side
channel display where it can run the special X11 clients which need
to complete before the regular clients are started. That feature is
present in Xwayland from current code upstream, and mutter can already
make use of it.
===Xwayland pkgconfig file===
That allows other packages to know about the Xwayland built options
and the Xwayland executable location so that Wayland compositors such
as gnome-shell/mutter can adapt to Xwayland features enabled at build
time.
For example, we could chose to have Xwayland installed in "libexec"
path rather than the common "bindir" path, and mutter could start
Xwayland from there (that requires changes in mutter though, but the
pkg-config for for Xwayland opens for that possibility)
===Maintainability===
With Xwayland receiving most of the attention upstream, that will
allow for new features to be available for Fedora users faster and
more easily.
== Scope ==
* Proposal owners: We would make Xwayland a separate package build
from git snapshots from upstream. That package would provide Xwayland
and Xwayland-devel (for the Xwayland pkg-config file).
The existing Xwayland build would be removed from the xorg-x11-server
package (stable releases branch).
* Other developers: Rebuild Xwayland dependent package if they want to
benefit from the new features exposed from the command line (e.g.
initfd)
* Release engineering: [https://pagure.io/releng/issues/9865 #9865]
* Trademark approval: N/A (not needed for this Change)
* Alignment with Objectives:
== Upgrade/compatibility impact ==
The standalone Xwayland package obsoletes the existing
xorg-x11-server-Xwayland package, so the upgrade would simply replace
xorg-x11-server-Xwayland with standalone Xwayland package.
Xwayland requires no configuration file, nothing needs to be updated
on the user side.
Features are added, not removed.
== How To Test ==
* Xwayland supports EGLStream so it needs non regression testing with
NVidia closed-source driver
* No config file are involved
* Test for non regression with X11 clients as compared with
xorg-x11-server-Xwayland from the stable branch
* Test must include demanding X11 clients such as games for non
regression (Steam?)
To ease testing, a COPR with the standalone package for Fedora 33 and
rawhide is available here:
https://copr.fedorainfracloud.org/coprs/ofourdan/Xwayland/
== User Experience ==
Users should not see any change (it's the same Xwayland program, just
built from a different branch from upstream).
== Dependencies ==
The current packages which list xorg-x11-server-Xwayland as dependency are:
* gamescope
* gnome-session-wayland-session
* kwin-wayland
* plasma-workspace-wayland
* sway
But the standalone Xwayland package would be a drop-in replacement for
xorg-x11-server-Xwayland (i.e. it provides xorg-x11-server-Xwayland)
so there is no impact on those packages.
* mutter would benefit from being rebuilt against the standalone
version of Xwayland to benefit from the initfd option.
== Contingency Plan ==
* Contingency mechanism: Switch back to building Xwayland from the
stable branch (xorg-x11-server-Xwayland).
Rebuild mutter to not use initfd
Downgrading to xorg-x11-server-Xwayland from the stable branch wpuld
require a user action, in case the contingency plan is triggered.
* Contingency deadline: beta freeze
* Blocks release: No
* Blocks product: No
== Documentation ==
There is no documentation change required.
--
Ben Cotton
He / Him / His
Senior Program Manager, Fedora & CentOS Stream
Red Hat
TZ=America/Indiana/Indianapolis