[Soci SLIP] FAQ Wayland/Mir

[Alex Palesandro]

Salve a tutti,

tempo fa, ho trovato queste FAQ chiarificatrici su wayland sul forum
di Phoronix e pensavo che magari potrebbe essere interessante
condividerle qui. Appena trovo il tempo le traduco e le metto sul
nostro sito. Purtroppo ho perduto il link alla discussione ma lo
recuperero appena ho un attimo. Spero che le troviate interessanti
come lo é stato per me.

Un caro saluto a tutti voi.

Alex Palesandro

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1.) Wayland is a library that allows you to send information to the
GPU in a standard fashion [like opengl library or openvg or GPU ASM]
to realize an specific task(in this case handling buffers/FB/input and
surfaces).
2.) LOL, i can do that with simple Opengl and Glut or even ASM!!!, yes
is true but if everyone handle the GPU in his own accord you will get
50 different incompatible render systems and 50 compositor totally
different.
3.) then OMG why not write a common library that do that, so we are
all in the same page?? welcome to Wayland, Wayland is exactly that
4.) Ok, so wayland is not a server/compositor/renderer/etc but is more
like a new GPU language designed to handle UI? i mean like OpenVG for
SVG graphics?, yes, but more exactly is to handle the minimal
coordination and allocation needed for GUI like
surfaces/input/overlays/layers and buffers
5.) So wayland actually don't draw anything? nope it doesn't have to,
wayland is the foundation barebone minimally needed to handle Gui in
the GPU, once wayland deliver you a functional surface you can do
whatever the hell you want with it as long as is valid for the GPU
ofc.
6.) So i can paint a wayland surface with Directx and OpenVG or using
my pro skills in AMD GPU ASM? hey, what about TGSI? yes in all as long
as you have proper driver support
7.) What is a compositor needed then? well the compositor is the
control center that manages the global "Desktop" concept and how all
those surface react and interact with each other[pretty much anything
that kwin/shell/compiz/etc do]
8.) Cool i wanna write my own compositor, where i can see an example
of how to do it?, well you can checkout weston which is exactly that a
runnable example of how to write a compositor for Wayland
9.) Weston was not part of wayland? no, those are 2 different projects
10.) so i don't need Weston? no, sure weston can be used and expanded
if you consider is good enough for your needs but is only an example
remember
11.) I wanna write a compositor, can i do it with threads/SIMD and
C++11 cool stuffs? sure, is up to you which tool use to make the best
of your compositor
12.) Im a game dev and i know many cool tricks to render more
efficiently in Opengl, can i use them? sure as long as is a GPU
complaint and the hardware supports it, you can composite or render
using any technique or language you feel is best for the task.
13.) wayland is a power hog, i kinda heard? nope, in fact is probably
the most power efficient protocol ever since it barely use the GPU to
start with
14.) ohh Yeah, wayland is not a server/compositor, so my compositor
and the toolkits are the actuals responsible for power efficiency,
right? yes, exactly since both the Toolkit and the compositor handle
the GPU operations and is ovbious if you boost the eyecandy and your
monitor size the GPU need more power to keep up, just like happens
with games.
15.) so Mir is the same stuff? no, Mir is an actual server/compositor
like X11 was but with less overhead and backtrips that happens to use
EGL too and is in a much earlier stage of development compared to
wayland.
16.) so this threaded compositing stuff for Mir should be compared to
wayland? i think is with other compositors, right? yes, you should ask
if kwin have threaded compositor or Mutter or Compiz, this has nothing
to do with Wayland

-- 
Alex Palesandro