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Clearing Up Wayland FUD, Misconceptions
An anonymous reader writes "In clearing up common misconceptions about Wayland (e.g. it breaking compatibility with the Linux desktop and it not supporting remote desktops like X), Eric Griffith (a Linux developer) and Daniel Stone (a veteran X.Org developer) have written The Wayland Situation in which they clearly explain the facts about the shortcomings of X, the corrections made by Wayland, and the advantages to this alternative to Canonical's in-development Mir."
Yes, I did it on my Raspberry Pi using the implementation of Weston that they discussed.
Making your ignorance plain is quite helpful to others in knowing to avoid you.
Yes, here we are, still with X. That doesn't make X good and it doesn't mean Wayland has made no progress. In fact the biggest driver of the Wayland transition is the wide availability of graphics accelerators that we didn't have back in 1997.
I won't really shed a tear when X is reduced to a library that sits on top of Wayland. I will enjoy improved performance and compositing that Wayland brings.
SurfaceFlinger. Of course, no one has actually adopted it. It's just prevalent because of Android.
I have never seen a good argument for this.
Read the article, then.
Well he gave an answer in the article: if you move to "fix X", you end up making X12. And when you do that, all the stakeholders in X come out of the woodwork and insist on preserving all the legacy parts of the system that, frankly, don't belong.
The way things have unfolded, X11 will become a library on top of Wayland. And that's perfectly fine.
Why not fix X?
The simplest and most obvious answer: it's easier and faster to just not bother and start from scratch.
In addition, X was originally written when networks and client systems were slow(er). Many of original design decisions are no longer appropriate with respect to the X server code complexity and maintenance requirements. A long (long) time ago, I wrote a program (called CXC - Concurrent X Control) to manage the low-level X protocol (think everything in the X11 Volume 0 book) and support transparent X traffic interception, blocking, redirection and insertion for a CBT application (called CAST) and, if I remember correctly, I remember wanting to off myself (or at least start drinking heavily) after trying to make sense of it all. Just my $.02.
It must have been something you assimilated. . . .
I've been a supporter of X11 for some time, but only as a user. I know how to use it, and it's more or less the same as it was ages ago. That heritage will be difficult to break, especially the network transparency it has (which some claim it doesn't really have if you're using DRI2 etc, but you don't have to use those).
However, I've read enough of these rants from both camps to start looking at this differently.
Back when X.org started, I was surprised that it became the norm so quickly. It did so because it worked, could be dropped in, and had some improvements.
AFAICT, Wayland isn't done yet. As a user, we're judging too early. Right now, they really only need to be convincing toolkit, driver, and X developers to get that development on board.
Once Wayland is drop-in usable with all common apps, it won't matter to the user except for how it performs in their various tasks. Once it gets to the point that, for example, a Ubuntu user could "sudo apt-get install wayland-somethingorother && dpkg-reconfigure somethingorother" to try it out, then we'll see if it lives up to the hype.
There are plenty of things it's saying it'll do that sound good. The parts that worry me from my naive perspective will be answered when it's usable, such as:
* apps having to do all the rendering. What about apps that don't do this now? Are we really going to force them through X, or will there be some middleware they can use, etc?
* the mini x server solution... there was a problem noted due to the change in coordinate systems. How will that be solved? What other problems may we run into? etc.
* the network transparency question. They haven't completed this yet. They may not ever do it (might be 3rd party). There's already some other attempts at this that show something can be done with it, but it's just not finalized yet. We just have to wait and see.
* remoting apps, and how that will relate to interoperability. Sounds like I'll be able to pull an X app up on my local Wayland desktop and have it displayed using the built in mini x server (maybe). What about the reverse? How do you export a Wayland app to a client that is only running X.org?
Seems to me that those are all solvable. Will the solutions pan out? well.. seems like those are still a work in (early) progress.
It's far enough now that there's no point in asking, "why do this?" or "why not fix X?" etc.. they're doing it, period. I'm done reading these things now, cause it's just a matter of "will it succeed?" (and it won't unless all the stuff people have been bitching about are solved, so who cares for now?)
* apps having to do all the rendering. What about apps that don't do this now? Are we really going to force them through X, or will there be some middleware they can use, etc?
Apps can use the Cairo library to render. That is what most of them are doing now anyway, since that is the only practical way to get antialiased lines and scalable images on X.
* the mini x server solution... there was a problem noted due to the change in coordinate systems. How will that be solved? What other problems may we run into? etc.
The problem was not really described correctly. The Wayland developers have this idea that applications should not know what their window positions are (I don't agree with this btw). X applications when they do the X api to figure out the window position are told it is at 0,0. On X an application wanting to make a popup menu not go off the screen, compared it's window position to the screen position, and thus knew where to place the menu (on Wayland the client says what position it wants the menu in (relative to it's window) and is told how it will be clipped, so the client can try another position). This means some errors with the popup of menus in X applications.
I was under the impression that they "fixed" this by allowing the X emulation to get at the secret information about where the window is. I complained on the mailing list that this means that X clients have a special privledge and they really should allow regular clients to get this secret info, but was ignored.
* the network transparency question. They haven't completed this yet. They may not ever do it (might be 3rd party). There's already some other attempts at this that show something can be done with it, but it's just not finalized yet. We just have to wait and see.
* remoting apps, and how that will relate to interoperability. Sounds like I'll be able to pull an X app up on my local Wayland desktop and have it displayed using the built in mini x server (maybe). What about the reverse? How do you export a Wayland app to a client that is only running X.org?
It looks like they are planning to use per-window RDP. This makes sense because the api and remote clients already exist, and you would run an X RDP client to display the Wayland windows.
It was invented here. A large share of the Wayland developers are ex-X11-developers. They know X11 from the inside.
The only argument I've seen is the lack of network transparency, often poorly worded with no actual technical argument behind it.
Sounds like you aren't interested in hearing the arguments, but I'll try. Practically all X11 apps can run remotely - the ones that can't are likely to be inherently limited, like video players or 3d first person shooters that have bandwidth and latency requirements that are transport constrained. Outside of those types and pathological configurations, remote X11 just works for all apps.
V) "Wayland can't do remoting." Wrong. Wayland should be BETTER than X at remoting, partially do its asynchronous-by-design nature. Wayland remoting will probably look a like a higher-performance version of VNC, a prototype already exists. And this is without us even giving it serious thought about how to make it better. We could probably do better if we tried.
"We haven't given it serious thought" is a particularly bad approach to convince people to quit bitching. Show us a well thought out plan to support per window/application remoting, not vnc-style desktop remoting and that will shut up practically everyone. Act like you really don't give a shit and nobody will have any confidence that it ever will "better than X."
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I've seen demos of Wayland that had per window remoting, including moving and cloning per window across different diplays. Wouldn't it be nice if xmove still actually worked for most applications? If you could just move your application across Xservers as you wished and didn't have to worry about temporary network outages killing you application? Well apparently Wayland can do that. So it seems to me that Wayland has potentially more to offer in terms of network transparency than X. It isn't done yet, so let's wait and see. Everything I've seen looks very promising.
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They have barely given it second thought because they've established that it can be done in principle, and it isn't the stuff they're working on (which is getting the actual display working cleanly and efficiently). They can worry about it when they've gotten the fundamentals pinned down. Do you really want excellent networking for a display system that doesn't display well, or is horribly slow? First things first and all that. As long as nothing they do makes it infeasible, or overly complicated there's no point in worrying about it till the very core functionality is working as they wish.
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