Linux Multi-Monitor Support Could Be Improved

[Tyler_K]

life with more than 2 screens, nvidia, and KDE is always... difficult. particularly the KDE part.

I'm quite happy how KDE handles multiple monitors with the radeon driver, what exactly are you missing?

mtk0 may have been referring specifically to the case of multiple X server display screens (i.e. :0.0 , :0.1, .... ) as opposed to the operation of multiple monitors under/constituting one X server display screen.

That is something I can attest too, though I suspect that it is due more to xrandr then it is the WM/DE.

Example: everything works perfectly when using an tri-headed eyefinity card, driven by the radeon driver. Add a second graphics adapter into the mix and you quickly run into headaches -- the 3 physical monitors on the eyefinity card (that constitue screen 0) are merged into one giant monitor as far as the WM/DE is concerned -- the result is that the taskbar is stretched across all of them; window maximization is no longer per monitor but rather across all 3; notifications and non-fullscreen windows that are opened end up appearing anywhere across the 3 monitors. Same thing occurs on the monitors (constituting screen 1) being driven by the second card. Moving the mouse cursor from the leftmost monitor of screen 1 results in the curson ending up appearing on the right edge of the leftmost monitor of screen 0, as opposed to (as expected) its rightmost monitor's right edge .... (this behaviour is actually fairly bizarre given the way the monitors are treated by the WM/DE under this dual graphics adapter/x-server display dual screen scenario). etc....

[JanC]

Some remarks:

1. Xinerama & nvidia twinview are deprecated ways to handle multiple screens; please use xrandr & make sure it works well with that, and tell the driver developers to support xrandr well (it makes no sense to support several competing multi-screen protocols). And if xrandr can't do what you need, please propose a change to xrandr—don't create yet another protocol...! (And of course use/propose whatever WM features are useful & appropriate.)
2. There is an X11 protocol extension that allows moving X clients to another X screen or even another X server (possibly running on another computer!), so I suppose with the help of the WM or a helper program it could be possible to add support for doing that using the mouse. Unfortunately the protocol requires support in both the X server, which is not really a problem, and the client (the application), which is a problem as almost no GUI framework supports it and application developers usually are not the people who want to implement X protocol extensions...

[Tyler_K]

And if xrandr can't do what you need, please propose a change to xrandr—don't create yet another protocol...! (And of course use/propose whatever WM features are useful & appropriate

Note that David Airlied has been working towards better multiple monitor xrandr support ... Phoronix has featured several news pieces about progress in this (and other closely related areas). Going by a message of Airlied's to K.P on the xorg m/l, I'd guess that finishing off all the bits required in xrandr (and elsewhere in the server) for proper multi-screen handling/support is about a year out ... if he doesn't burn out first (paraphrasing).

There is an X11 protocol extension that allows moving X clients to another X screen or even another X server (possibly running on another computer!), so I suppose with the help of the WM or a helper program it could be possible to add support for doing that using the mouse. Unfortunately the protocol requires support in both the X server, which is not really a problem, and the client (the application), which is a problem as almost no GUI framework supports it and application developers usually are not the people who want to implement X protocol extensions...

I imagine you are referring to Xpra and shifter (or whatever the applet is called now)

[Tyler_K]

Going by a message of Airlied's to K.P on the xorg m/l, I'd guess that finishing off all the bits required in xrandr (and elsewhere in the server) for proper multi-screen handling/support is about a year out ... if he doesn't burn out first (paraphrasing).

Okay, found it (well, actually, a second too, cause it provides a tidbit of further information about the direction and manner of progression):

- http://lists.x.org/archives/xorg-dev...ne/031520.html
- http://lists.x.org/archives/xorg-dev...ly/032246.html

[F i L]

EASY SOLUTION TO MULTI MONITOR DISPLAY

For those of you, like me, that use Multiple monitors, an easy solution is to just disable the secondary monitor before playing games. Here's how:

$ xrandr --output DFP2 --off

Obviously, you'll need to change 'DFP2' to whatever your second monitor is (which can be found bye simply typing '$ xrandr').
However, if you second monitor is a different size, you may end up needing to adjusts the size of the primary when disabling the second monitor. For example:

$ xrandr --output DFP2 --off --output DFP1 --mode 1920x1080

To enable the second monitor, simply set it's mode and position:

$ xrandr --output DFP2 --mode 1280x800 --pos 304x1080

Here I'm setting the position (--pos) manually, but there are simple commands (--left, --bottom) that make it easier.


GNOME-SHELL USERS

I recommend installing the MyLauncher Extension and setting up a couple 'Turn Monitor Off/On' menu options for convenience.


I hope this helps anyone browsing for solutions to this in the future.

[JanC]

I imagine you are referring to Xpra and shifter (or whatever the applet is called now)

No, I was referring to an X11 protocol extension (that was never widely used, and I'm not sure what X servers actually supported it), Xpra is sort of an X server proxy instead (which means it works without support from the X clients).

[Tyler_K]

Ahh, okay, thanks. I hadn't heard of it before.

[JanC]

FWIW: I think it was called "Display Migration Protocol" or something like that.

[Tyler_K]

Thanks. Not much on google for that, but the second hit (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=214889 ) refers to it, as well as to a libdisplaymigration ... googling the latter reveals what looks to be distro packages for it (e.g. https://www.google.com/search?q=libdisplaymigration ) and a few more misc. threads.