[T.J. ] Hi Jude!




Wayland is basically just that--a complete rewrite of X, built around design
requirements that were not present when X11 was designed. Think of Wayland
as X12, and think of Xwayland as the X11 compatibility layer.

[T.J. ] Yes, I know. =)



Also, userspace mode setting these days is a racy prospect at best that is
incredibly difficult to coordinate without the kernel's help. This is
because the sequencing of low-level hardware events from contemporary video
devices (i.e. DMA, power changes, suspend/resume, external displays) can
interfere with the sequence of user mode setting ioctl()'s to the point
where the state of the video hardware can easily get out-of-sync with
userspace's understanding of it, causing userspace to issue ioctls that
leaving you with a locked-up display. The kernel *should* be handling
mode-setting requests these days, because only the kernel is in a position
to correctly sequence mode-setting requests with ongoing low-level hardware
events (such as by blocking or deferring the relevant hardware interrupts).



This isn't a Linux-only thing, by the way. All the BSDs have or (in
NetBSD's case) will soon have KMS enabled by default. Windows NT has had it
for decades.


[T.J. ] That is like saying that everyone uses the same mouse. They might
work the same to the average person, but a developer knows the difference.
Wayland at present only works on Linux and it is not being designed with
portability in mind. The actual Wayland devs are working only with Linux
and that is really all they are concerned with. Granted, there are efforts
to patch Wayland for other systems, but they not really high priority.