Revision as of 18:52, 30 March 2015

Wayland By Default

Summary

Change the default session selection in gdm to prefer the Wayland-based GNOME session over the X11-based one.

Owner

Name: Matthias Clasen
Email: mclasen@redhat.com
Release notes owner:
Product: Workstation
Responsible WG: Workstation

Current status

Targeted release: Fedora 23
Last updated: 2015-03-25
Tracker bug: <will be assigned by the Wrangler>

Detailed Description

We will change the default session in the gdm session selector to be the Wayland session, if both are available. If a user makes an explicit choice, we will still remember it and keep using the same session the next time he logs in.

Benefit to Fedora

Using Wayland instead of X gives a much better basis for isolating applications from each other and the system.

Scope

Proposal owners:
- Rename the gnome-wayland.session file to gnome.session and the current gnome.session file to gnome-x.session. At the same time, change the display names around to be just 'GNOME' for the default, and 'GNOME on X11' for the X11-based session.
- Make gdm hide Wayland sessions from the session chooser if we know they will not work (because the login screen had to fall back to X)
- Close all remaining feature parity gaps between the Wayland and the X11 session:
  - input methods
  - on-screen keyboard
  - hi-dpi support
  - clipboard proxy for xwayland
  - attached modal dialogs
  - tablet support
  - startup notification
  - touch proxy for xwayland
  - accessibility features
  - output rotation

Other developers: GTK+ applications that use X11-specific APIs need to be patched to explicitly use the GDK X backend

Release engineering: No release engineering changes needed

Policies and guidelines: No policy or guideline changes needed

Upgrade/compatibility impact

Systems using certain graphics hw or graphics drivers (matrox, qxl) may have problems running the Wayland session. In these (rare) cases, users may have to configure gdm to use X11 (although automatic fallback should work most of the time). If we don't manage to close all the feature parity gaps entirely, then users relying on those features may have to choose the X11-based session.

How To Test

Boot a fresh F23 workstation install.
Verify that the login screen is running under Wayland (you can do so by looking for a process called gdm-wayland-session in ps -ef output)
Verify that the session chooser offers 'GNOME', 'GNOME on X11' and 'GNOME Classic', and that 'GNOME' is selected by default.
Log into all three of these sessions and verify that 'GNOME' gives you Wayland (you can verify this by bringing up the GTK+ inspector in a gtk3 application and checking what backend is used), while the other two end up with X11.

Change the gdm configuration by adding WaylandEnable=false and reboot
Verify that the login screen comes up under X
Verify that only X-based sessions are offered in the session chooser

Log into the Wayland-based session again
Use the desktop normally, and verify that there are no obvious instabilities, or Wayland-specific bugs or performance problems

User Experience

The user experience of the Wayland session is identical to that of the X session.

Dependencies

The tasks lists in the Scope section are spread across a number of upstream modules and packages: gtk3, gnome-shell, mutter, libinput, Xorg, gdm.

Contingency Plan

Contingency mechanism: Revert the changes to the session files, thereby keeping the X-based session as the default
Contingency deadline: beta
Blocks release? no
Blocks product? no

Documentation

TBD

Release Notes

TBD

[[Category:SystemWideChange]

@@ Line 18: / Line 18: @@
 == Current status ==
 * Targeted release: [[Releases/23 | Fedora 23 ]]
 * Last updated: 2015-03-25
 <!-- After the change proposal is accepted by FESCo, tracking bug is created in Bugzilla and linked to this page
 Bugzilla states meaning as usual:
 NEW -> change proposal is submitted and announced
@@ Line 34: / Line 34: @@
 We will change the default session in the gdm session selector to be the Wayland session, if both are available. If a user makes
 an explicit choice, we will still remember it and keep using the same session the next time he logs in.
 == Benefit to Fedora ==
 Using Wayland instead of X gives a much better basis for isolating applications from each other and the system.
 <!-- What is the benefit to the platform?  If this is a major capability update, what has changed?  If this is a new functionality, what capabilities does it bring? Why will Fedora become a better distribution or project because of this proposal?-->
 == Scope ==
 * Proposal owners:
 ** Rename the gnome-wayland.session file to gnome.session and the current gnome.session file to gnome-x.session. At the same time, change the display names around to be just 'GNOME' for the default, and 'GNOME on X11' for the X11-based session.
 ** Make gdm hide Wayland sessions from the session chooser if we know they will not work (because the login screen had to fall back to X)
 ** Close all remaining feature parity gaps between the Wayland and the X11 session:
@@ Line 87: / Line 86: @@
 == Dependencies ==
 The tasks lists in the Scope section are spread across a number of upstream modules and packages: gtk3, gnome-shell, mutter, libinput, Xorg, gdm.
 == Contingency Plan ==
@@ Line 105: / Line 104: @@
 <!-- When your change proposal page is completed and ready for review and announcement -->
 <!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler -->
 <!-- The Wrangler announces the Change to the devel-announce list and changes the category to Category:ChangeAnnounced (no action required) -->
 <!-- After review, the Wrangler will move your page to Category:ChangeReadyForFesco... if it still needs more work it will move back to Category:ChangePageIncomplete-->
 [[Category:SystemWideChange]

Search

Changes/WaylandByDefault: Difference between revisions