> In a full-screen case AFAIK it's possible to skip the compositing step with X11, and maybe with Wayland too. This is the trivial optimization all Wayland com

> In a full-screen case AFAIK it's possible to skip the compositing step with X11, and maybe with Wayland too. This is the trivial optimization all Wayland compositors do. The neater trick is to do this for non-fullscreen content - and even just parts of windows - using overlay planes. Some compositors have their own logic for this, but libliftoff aims to generalize it. Zero-copy is not really ambiguous, but to clarify: Wayland protocols are designed to maximize the cases where a buffer rendered by a client can be presented directly by the display hardware as-is (scanned out), without any intermediate operations on the content. Note "maximize" - the content must be compatible with hardware capabilities. Wayland provides hints to stay within capabilities, but a client might pick a render buffer modifier/format that cannot be scanned out by the display hardware. GPUs have a lot of random limitations.