Talk:Extreme Multihead

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Latest comment: 4 January 2021 by Paulatz in topic Using an HDMI output

This is a first draft

Multihead Consolidation

There already exist several attempts at documenting Multihead configuration each adding new perspectives but frequently repeating content from other pages (in different words) propose

  1. providing an overview of X (and Multihead) configuration leading to detailed explanations
  2. reduce the focus of individual pages to limit length, content duplication & complexity

Possibly have composite pages address possible options and whys/wherefors -> how-to-pages with limited focus Sorry haven't time to pursue this right now (still building systems) - back soon Blacktav (talk)

Well, I find there are many repeat pages too. Sorry I can only translate them to Chinese while my English is not good. Hope someone can get it done. -- Acgtyrant (talk) 10:18, 16 May 2013 (UTC)Reply[reply]

dummy xorg driver

I have never been able to make dummy xorg driver to work together with a real graphic card. Anyway, this is an example section that could be used. For me, this always resulted in xorg not starting or, worst, using the dummy device.

You should probably also get the initial xorg configuration (Xorg -configure :2) and put it in anotehr file (es /etc/X11/xorg.conf.d/90-dummy.conf) adding the

       Option "primary" "true"
       Option  "disable" "false"

to the real physicial screen, to be sure that it is used. In this way, this dummy configuration should at least be harmless.

Section "Monitor"
Identifier "Monitor1"
HorizSync 28.0-80.0
VertRefresh 48.0-75.0
Modeline "1920x1080_60.00" 172.80 1920 2040 2248 2576 1080 1081 1084 1118 -HSync +Vsync

Section "Device"
Identifier "Card1"
Option "NoDDC" "true"
Option "IgnoreEDID" "true"
Driver "dummy"

Section "Screen"
DefaultDepth 16
Identifier "Screen1"
Device "Card1"
Monitor "Monitor1"
    SubSection "Display"
    Depth 16
    Modes "1920x1080"

Section "ServerLayout"
  Identifier   "Main"
  Screen       0 "Screen0"
  Screen       1 "Screen1" rightof "Screen0" # assuming that the real screen is screen0
  Option         "Xinerama" "1"  # enable XINERAMA extension.  Default is disabled.

Paulatz (talk) (forgot to sign)

Using an HDMI output

Hello, in Extreme Multihead#Using an HDMI output section, it is mentioned that some programs will not recognize the screen, but I found a fix that works for me on my laptop with i5-4210M cpu. I am not sure if this will work for everyone.

According to Kernel mode setting#Forcing modes, you can set kernel parameter "video=<conn>:e" to force output. <conn> is connector name, you can find it with command

for p in /sys/class/drm/*/status; do con=${p%/status}; echo -n "${con#*/card?-}: "; cat $p; done

For my laptop the names for free outputs are "HDMI-A-1" and "VGA-1".

-- Cges30901 (talk) 17:21, 20 December 2020 (UTC)Reply[reply]

It does work for me, however I get another bunch of glitches (i.e. screen not turning back on after suspend, login screen resized to some small resolution). Ideally one would want HDMI enabled but without any modeline to reduce confusion at the X server level. Paulatz (talk) 07:34, 4 January 2021 (UTC)Reply[reply]
P.S. One could also just do <conn># echo on > /sys/kernel/debug/dri/0/HDMI-A-2/force</conn> but this does not seem to work for me. More precisely: I am able to turn the output on and off freely in this way, but only if I had specified t kernel parameter above, otherwise it has no effect. Paulatz (talk) 07:47, 4 January 2021 (UTC)Reply[reply]
P.P.S It seems that I was doing something wrong in the past, because now setting the force file to "on" at runtime (which does require root) seems to work seamlessly. If someone confirms, I'll just add it to the page Paulatz (talk) 09:41, 4 January 2021 (UTC)Reply[reply]