Linux Graphics / GPU / X / Wayland Architecture

What is Wayland Architecture?


From wiki:

To quote:

Wayland is a protocol that specifies the communication between the display server and its clients.[3] It was initially designed by Kristian Høgsberg as a replacement for the X Window System. In stark contrast to the latter, Wayland specifies that the clients are responsible for the drawing of their window borders and their decorations and the clients will render without detour directly into their own buffer located in the graphics memory, through the use of EGL with some additional Wayland-specific extensions to EGL.

And the details are partly shown below:

① The evdev module of the Linux kernel gets an event and sends it to the Wayland compositor.
② The Wayland compositor looks through its scenegraph to determine which window should receive the event. The scenegraph corresponds to what’s on screen and the Wayland compositor understands the transformations that it may have applied to the elements in the scenegraph. Thus, the Wayland compositor can pick the right window and transform the screen coordinates to window local coordinates, by applying the inverse transformations. The types of transformation that can be applied to a window is only restricted to what the compositor can do, as long as it can compute the inverse transformation for the input events.
③ As in the X case, when the client receives the event, it updates the UI in response. But in the Wayland case, the rendering happens by the client via EGL, and the client just sends a request to the compositor to indicate the region that was updated.
④ The Wayland compositor collects damage requests from its clients and then re-composites the screen. The compositor can then directly issue an ioctl to schedule a pageflip with KMS

More resources below:

Wayland Input Method System Proposal

The Wayland Compositor Architecture

What does EGL do in the Wayland stack

Introduction to Wayland

How to embrace wayland for Tizen

Why Wayland is better:

Compositing after X KWin on the Road to Wayland

Wayland Vs X Server Architecture (in Greek, can use Google Chrome to view, which will allow you to translate)

Wayland: Choosing a better input method architecture

David Airlie: Teaching the X server new tricks (LCA 2013)


Welcome to Chromium’s Ozone-Wayland (September 18, 2013)

Wayland on Android:

Wayland’s 1.0 milestone fixes graphics protocol;zoom=2

X on Wayland

Wayland prototype for rendering software that runs remotely


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