Wayland

Some Wayland notes for me

Design and Terminology

Seats are generally input devices: mices, touchscreens, touchpads, etc...

The Wayland Compositor manages and dispatches input events from seats to Wayland Clients. The Compositor also renders and places the windows onto the screen, a process called compositing.

Hardware and Kernel

Hardware can only be accessed by the kernel:

• DRM (direct rendering manager) is used to issue commands to the GPU.
• KMS (kernel mode setting) is used to query for these devices.
• evdev abstracts access to input devices

DRM:

• /dev/dri/card*: priviledged actions like modesetting
• /dev/dri/render*: unpriviledged actions like rendering

evdev:

input events through /dev/input/event*

Userspace

DRM -> libdrm Mesa -> OpenGL, Vulkan, and GBM (Generic Buffer Management) libinput -> evdev (requires priviledged access) (e)udev -> enumeration and reporting of new devices xkbcommon -> scancodes into key "symbols" and state machine for modifiers pixman -> pixel manipulation (buffers, math, etc...) libwayland -> implementation of wayland protocol and more...

Protocol