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Linux display server is what and what display servers have, for this problem, this article details the corresponding analysis and solutions, hoping to help more small partners who want to solve this problem find a simpler and easier way.

What is a Display Server in Linux?

A display server is a program whose primary task is to coordinate input and output between clients and other operating systems, hardware, and each other. Display servers communicate with their clients through the Display Server Protocol.

Display servers are a key component of any graphical user interface, especially windowing systems. It is the basic component of the graphical user interface (GUI), located between the GUI and the kernel. So, with Display Server, you can use your computer with a GUI. Without it, you will only be able to use the command line interface.

It is important not to confuse display servers with desktop environments. Desktop environments (Gnome, KDE, Xfce, MATE, etc.) use an underlying display server.

For example: Ubuntu 21.04 now enables Wayland by default https://www.linuxmi.com/ubuntu-21-04-linux-5-10-lts-wayland.html

Display servers communicate with their clients through the Display Server Protocol. There are three display server protocols available in Linux. X11 and Wayland are two of them. The third Mir is beyond the scope of this article.

X Window System, X.Org, X11 Introduction

The X Window System (often referred to simply as X or X11) is really old. It originated in 1984 and eventually became the default window system for most UNIX-like operating systems, including Linux.

X.Org Server is a free open source implementation of the X Window System Display Server managed by the X.Org Foundation. It is an application that interacts with client applications via the X11 protocol to draw content on the display and send input events such as mouse movements, clicks, and keystrokes. Typically, an X server will be started and it will wait for client applications to connect to it. Xorg is based on a client/server model, thus allowing clients to run locally or remotely on another computer.

In the X11's design, it wasn't obvious that applications and displays didn't have to be on the same computer. When X was developed, it was common for X servers to run on workstations, while users ran applications on remote computers with more processing power.

X11 is a network protocol. It describes how messages are exchanged between the client (application) and the display (server). These messages usually come with primitive draw commands such as "Draw box,""Write these characters here,""Left mouse button clicked," etc.

But X11 is old, and most of the features provided by the X server protocol are no longer used. Almost all of the work done by X11 has been redistributed to individual applications and window managers. However, all of these old features remain, putting stress on all of these applications and compromising performance and security.

Wayland, the Next Generation Display Server

Wayland was started as a solo project in 2008 by Kristian Hogsberg, a developer at X.Org. It is a communication protocol that specifies communication between a display server and its clients. Wayland was developed as a free, open source, community-driven project to replace the X Window System (also known as X11 or Xorg) with a modern, secure, and simple window system.

In Wayland, compositors are display servers. Composer is a window manager that provides an off-screen buffer for each window for your application. The window manager composes the window buffers into images representing the screen and writes the results to display memory.

The Wayland protocol allows compositors to send input events directly to clients and clients to send corruption events directly to compositors.

As in the X case, the client updates the user interface (UI) in response to receiving an event. However, in Wayland, rendering occurs in the client, and the client simply sends a request to the compositor to indicate the updated region.

Wayland's main advantage over X is that it starts from scratch. One of the main reasons for X's complexity is that its role has changed over the years. As a result, X11 today largely acts as "a really bad" communication protocol between clients and window managers.

Wayland also excels in security. With X11, you can perform an operation called "keylogging" by allowing any program to exist in the background and read what happens to other windows open in the X11 zone. With Wayland, this doesn't happen at all, because each program works independently.

summary

However, the X Window System still has many advantages over Wayland. Even though Wayland eliminates most of Xorg's design flaws, it has its own problems. Even though Wayland has been going on for more than a decade, things are still not 100% stable. As of 2020, most video games and graphics-intensive applications for Linux will still be written for X11. In addition, many closed-source graphics drivers, such as NVIDIA GPU drivers, do not yet fully support Wayland.

X does not last, Wayland can be improved in many ways. But to date, the vast majority of native applications available have been written for Xorg. Xorg needs to be maintained until all of these applications are ported. Wayland isn't very stable compared to Xorg.

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