Add support for higher number of monitors and GPU screens

[GermanAizek]

@metux,
Most owners display walls complain that Xorg does handles poorly lots of displays, so they choose Wayland.

Maybe need changes this macros?

https://github.com/X11Libre/xserver/blob/40dc3b6419a5c72242c28724f1f78ff39a726af6/include/misc.h#L84-L95

Example photos LCD display walls:

[Samueru-sama]

Can you actually merge multiple displays as one with wayland? I wasn't able to do that with sway with the 3 displays that I have.

Doing a quick search I can't find any info either: https://www.reddit.com/r/wayland/comments/108dgwc/combine_monitors_to_single_screen/

[dec05eba]

MAXSCREENS iirc is not the max number of monitors, it's the max number of x11 screens which is a different thing. With that many screens I believe the real limit is the resolution. I believe it stops behaving correctly if you go above 2^15 (32768) in either width/height or x/y coordinates.
Also I dont believe in your statement:

Most owners display walls complain that Xorg does handles poorly lots of displays, so they choose Wayland.

[HaplessIdiot]

This is a great idea reminds me of how AMD eyefinity used to work with triple monitors. @dec05eba do you know where in the code it defines the variable type for the x/y we could just change it to another variable type to do insanely high virtual resolutions for downsampling perhaps. doom 2 at 65536x the max size of the variable could be interesting to try.

[dec05eba]

do you know where in the code it defines the variable type for the x/y we could just change it to another variable type to do insanely high virtual resolutions for downsampling perhaps.

It's defined in the protocol itself, not just the xorg server. So you cant change it without breaking clients. You have to change it in libx11/libxcb as well and recompile client software and make sure they dont save the data internally as signed/unsigned short either.

[HaplessIdiot]

thanks for the super fast response it figures its more complex than swapping out a variable. So we need to make changes from libx11/libxcb and make sure it stays a short absolute unsigned number heard that! I'm gonna try and find the lines where its referenced and post them here to help then ill try and draft code something up in my private branch and see if it compiles. 65k doom sounds too cool to not try for me. imagine the youtube news when x11libre runs doom 2 at 65k that will pull some eyes for sure. Then we can get somebody to pay the 1500$ to run doom at 65k on the dome in las vegas to market x11libre

[smj-cc]

If the pixels on the dome (or at the airport, for that matter) are as big as your fist, is that a problem? Are you supposed to be able to walk up to these things and concentrate on two square inches, or are they meant to be viewed from a distance?

[HaplessIdiot]

If the pixels on the dome (or at the airport, for that matter) are as big as your fist, is that a problem? Are you supposed to be able to walk up to these things and concentrate on two square inches, or are they meant to be viewed from a distance?

okay thats a valid point I dont think the dome is even high enough res to do it now that you mentioned it. Im sure we can come up with some fun use cases for it when it works.

[HaplessIdiot]

@dec05eba This is a search of variables i found with "max_resolution" OR "MAX_RESOLUTION" OR "maxRes" OR "MAX_RES" are there any other variables that i need to find? Im gonna try and get started with these for now.

[dec05eba]

@dec05eba This is a search of variables i found with "max_resolution" OR "MAX_RESOLUTION" OR "maxRes" OR "MAX_RES" are there any other variables that i need to find? Im gonna try and get started with these for now.

That search looks messed up, its showing results from elsewhere. This is one place where resolution of the x11 screen (which is all monitors) is defined as short (max value 32768): https://github.com/X11Libre/xserver/blob/master/include/scrnintstr.h#L514. But anyways, I dont buy the premise of this issue. Even if you have many monitors its unlikely that they are high resolution enough to have a combined resolution of higher than 32768. But I cant confirm since I dont have a billion monitors.
But one more issue is that max framebuffer resolution in gpus is usually 16384, so even if you increase the limitation in the x server you are limited by the gpu. This will always be the case when all monitors are combined into one large framebuffer in the x server.

[HaplessIdiot]

@dec05eba This is a search of variables i found with "max_resolution" OR "MAX_RESOLUTION" OR "maxRes" OR "MAX_RES" are there any other variables that i need to find? Im gonna try and get started with these for now.

That search looks messed up, its showing results from elsewhere. This is one place where resolution of the x11 screen (which is all monitors) is defined as short (max value 32768). But anyways, I dont buy the premise of this issue. Even if you have many monitors its unlikely that they are high resolution enough to have a combined resolution of higher than 32768. But I cant confirm since I dont have a billion monitors.

i updated the search link i was going to try and make the variable a uint16 since that is unsigned and should be safe as a drop in change rather than short or int16. then when that gets done i can try and figure out how to downscale a virtual desktop at that resolution to 1440p or something normal. I want it to default to downsampling to the max size of the framebuffer of the gpu and i want to code something to detect the framebuffer max to prevent crashing.

[dec05eba]

i updated the search link i was going to try and make the variable a uint16 since that is unsigned and should be safe as a drop in change rather than short or int16. then when that gets done i can try and figure out how to downscale a virtual desktop at that resolution to 1440p or something normal. I want it to default to downsampling to the max size of the framebuffer of the gpu and i want to code something to detect the framebuffer max to prevent crashing.

Oh sorry I forgot to include the link to where it's defined as short in the code: https://github.com/X11Libre/xserver/blob/master/include/scrnintstr.h#L514 (I updated my comment)

[HaplessIdiot]

thanks a ton this saves me so much time to converse with you! the first commit i made for X11Libre/xserver#122 was mainly possible because you knew exactly where the code was that needed changed. Your secondhand knowledge of where everything is located is paramount for helping work get moving.

[metux]

@metux, Most owners display walls complain that Xorg does handles poorly lots of displays, so they choose Wayland.

Maybe need changes this macros?

That's the number of separate X screens (per server), not the number of outputs/monitors.
More than one is pretty unusual today - most people using randr to certain areas of one screen to separate outputs/monitors (so windows can also span across monitors, even though they can only be on one screen).

[callmetango]

Hello @GermanAizek,

thank you for reporting the issue. Could you please update the description using the template given in #132 ?

Please add your content in the template fields enclosed with {{ and }} and remove the curly braces.

Could you please mark the checkboxes in the Extra fields section too by replacing the space with an x?

Thanks for your help.

[callmetango]

Moving this to X11Libre Ideas · Discussions · GitHub to further refine it.

[callmetango]

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