RHEL 8 New Features for Experienced Linux Administrators
- SectionDisplaying the Desktop with Wayland and X
- Guided Exercise: Displaying the Desktop with Wayland and X
- Managing User Authentication with Authselect
- Guided Exercise: Managing User Authentication with Authselect
- Configuring NTP with Chrony
- Guided Exercise: Configuring NTP with Chrony
- Managing Python Versions in Red Hat Enterprise Linux 8
- Guided Exercise: Managing Python Versions in RHEL 8
- Lab: Adapting to Core System Changes
- Summary
Abstract
| Goal | Manage core system components that have had significant changes, including the graphical desktop infrastructure, user authentication configuration, the NTP service, and Python version selection. |
| Objectives |
|
| Sections |
|
| Lab |
Adapting to Core System Changes |
Objectives
After completing this section, students should be able to:
Explain the difference between Wayland and the legacy X Window System
Configure a server or user session to use either Wayland or X
Wayland Windowing System
Wayland is a client/server windowing system designed to replace X11. The performance improvements of Wayland over X11 are derived from the simplification of the architecture.
Wayland Components
Wayland Compositor - combines the display server and compositor roles.
Wayland Client - the graphical application communicating with the Wayland Compositor. Wayland clients are responsible for performing their own rendering.
Linux Kernel - responsible for communicating between the Wayland Compositor, the event device driver handling input and output devices (evdev), and the kernel mode-setting API (KMS) for resolution, depth and refresh.
Switching to Wayland
Wayland is not an extension of the X11 window system, but a replacement for it.
Reasons to Switch to Wayland
The X display server has become a bottleneck between clients, the compositor, and the kernel.
X has legacy code such as the rendering API that is rarely used but must remain to conform to the X11 protocol.
Most graphical desktops have a choice of compositor, which adds latency because the X display server must send the content to the compositor process for rendering, then return the rendered content to the X server to be displayed.
X11 Application Compatibility
X11 applications that have not been migrated to Wayland can still run in a Wayland compositor. XWayland is an Xorg server that runs as a Wayland client. When an X11 application is launched, the Wayland Compositor will call XWayland to handle the application's requests. XWayland is provided by the xorg-x11-server-Xwayland package.
Remote Rendering
Wayland is not network transparent, and does not support remote rendering. Instead, a remote rendering server, such as RDP or VNC desktop protocols, can be run on top of Wayland. It is also expected that upstream Wayland compositors will be created that include a remoting protocol.
Verify Wayland is Being Used
Use the following steps to determine whether your desktop is using Wayland.
[user@demo ~]$loginctlSESSION UID USER SEAT TTY21000 user seat0 tty2 c1 42 gdm seat0 tty1 2 sessions listed.[user@demo ~]$loginctl show-session 2 -p TypeType=wayland
Gnome 3 uses Wayland by default.
However, not all applications in Red Hat Enterprise Linux 8 have been migrated.
Unmigrated applications are managed with an XWayland driver to provide their X server requirements.
If Wayland is incompatible with your graphics hardware or application, it is a simple process to revert to using Xorg.
Uncomment the following line in /etc/gdm/custom.conf and then reboot your machine.
#WaylandEnable=false
This forces GDM to use Xorg and also sets the default session to Xorg.
