Switch 4 displays

Hal V. Engel hvengel at astound.net
Wed Nov 26 10:31:33 PST 2008

On Wednesday 26 November 2008 00:36:13 scorbo wrote:
> Hi,
>   I have a Nvidia Quadro NVS440 graphic cards with 4 screens and I would
> like to switch display like I want (display :0.0 becomes :0.1 so :0.1
> becomes :0.0). I've tried with xrandr but the Nvidia Property driver
> indicates only one screen and not 4. 

This driver does not support XRandR 1.2 at all.  It's "native" (but property) 
multihead mode is called TwinView.  TwinView has a number of issues caused by 
the "only one screen" indication such as not being able to calibrate the 
individual displays (IE. you can't set separate video card gamma tables for 
each display).  

It appears that what you want is Zaphod mode.  You should be able to do this 
with the nvidia driver but not using TwinView.  The basic setup would be the 
same as an xinerama setup but with xinerama turned off.  That is you would 
have 4 monitor, screen and device sections - one of each for the four 
displays.  To turn xinerama off you would need something like this:

Section "ServerFlags"
  Option "Xinerama" "false"

> Therefore I've installed Nouveau but
> it doesn't support this card. In addition I've read that xrandr does't
> support multi GPU and multi card (this card has two GPU). I've also tried
> with a Nvidia 290 graphic card and the Nouveau driver and it works but
> there is only two displays and the display has been configured in Xinerama
> mode and I need independent display.
>   I've read that xrandr 1.3 with Xorg 7.5 will support multi board and
> multi gpu, is it exact ? Is there another solution to switch display ?
> Thanks
> Christophe P.

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