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I have a video card with 2 video outputs. I want to run 2 instances of xinit and draw 2 different displays. I want one display to be output to one video out and the other to go to the other video out. I'm running CentOS 6.4. I have my xorg file set up for both video outputs correctly, if I run startX I see them both configured correctly, one of them is screen 0 and the other is screen 1. However, if I run xinit -- :0.0 to output for one display, this works and displays on the primary monitor. Then I run xinit -- :1.1 for the other display. This triggers the second monitor to display correctly, but the first display then goes completely blank. Both xinit processes are still running.

xorg.conf is set up so that each monitor is on separate screens rather than one screen that goes across both. These are screen0 and screen1. Here's the xorg (I left out the keyboard/mouse sections):

Section "ServerLayout"
  Identifier      "Layout0"
  Screen        0 "Screen0" 0 0
  Screen        1 "Screen1" 0 0
  InputDevice     "Keyboard0" "CoreKeyboard"
  InputDevice     "Mouse0" "CoreMouse"
  Option          "Xinerama" "0"
EndSection

Section "Monitor"
  Identifier      "Monitor0"
  VendorName      "Unknown"
  ModelName       "Unknown"
  HorizSync       31.5 - 98.7
  VertRefresh     50.0 - 85.0
  Option         "DPMS"
  ModeLine       "1440x900" 106.5 1440 1520 1672 1904 900 903 909 932 -hsync +vsync
EndSection

Section "Monitor"
  Identifier      "Monitor1"
  VendorName      "Unknown"
  ModelName       "Unknown"
  HorizSync       31.5 - 98.7
  VertRefresh     50.0 - 85.0
  Option         "DPMS"
  ModeLine       "1440x900" 106.5 1440 1520 1672 1904 900 903 909 932 -hsync +vsync
EndSection

Section "Device"
  Identifier      "Device0"
  Driver          "nvidia"
  VendorName      "NVIDIA Corporation"
  BoardName       "GeForce GTX 480"
  Screen          0
  Option          "UseEDID" "false"
  Option          "UseEDIDFreqs" "false"
EndSection

Section "Device"
  Identifier      "Device1"
  Driver          "nvidia"
  VendorName      "NVIDIA Corporation"
  BoardName       "GeForce GTX 480"
  Screen          1
  Option          "UseEDID" "false"
  Option          "UseEDIDFreqs" "false"
EndSection

Section "Screen"
  Identifier      "Screen0"
  Device          "Device0"
  Monitor         "Monitor0"
  DefaultDepth    24
  Option          "Stero" "0"
  Option          "metamodes" "1440x900"
  Option          "SLI" "Off"
  Option          "MultiGPU" "Off"
  Option          "BasicMosaic" "off"
  Option          "ModeValidation" "AllowNonEdidModes"
  Subsection
    Depth         24
    Modes         "1440x900"
  EndSubsection
EndSection

Section "Screen"
  Identifier      "Screen1"
  Device          "Device1"
  Monitor         "Monitor1"
  DefaultDepth    24
  Option          "Stero" "0"
  Option          "metamodes" "1440x900"
  Option          "SLI" "Off"
  Option          "MultiGPU" "Off"
  Option          "BasicMosaic" "off"
  Option          "ModeValidation" "AllowNonEdidModes"
  Subsection
    Depth         24
    Modes         "1440x900"
  EndSubsection
EndSection

EDIT: More info. Turns out they both run but one of them is on vt07 and the other is on vt08. If I use CTRL+ALT+F7 (or F8) I can swap which monitor displays and which one is blank, but one of them is always blank. I tried to add to the commands to specify the virtual terminal: xinit -- :0.0 vt07 and xinit -- :1.1 vt07. But when I do this, the 2nd one will not start, giving an error that it cannot find any screens. Starting to wonder if this is a constraint of xinit, possibly due to both video outputs coming from a single video card.

How do I run both xinit routines at the same time?

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  • 1
    For all intents and purposes you have two separate displays, so try :1.0 instead of :0.1. Better yet, edit /etc/X11/xinit/xserverrc. – lcd047 Jun 6 '15 at 17:19
  • Do I need to do :0.0 and :1.1? I'm under the impression the number after the dot specifies the screen that's defined in the xorg.conf, which I have '0' defined to go to one video output and '1' to the 2nd video output. Is that correct? – Dtor Jun 6 '15 at 17:21
  • 2
    :0.0 is screen 0 of server 0, :1.0 is screen 0 of server 1. They aren't related. – lcd047 Jun 6 '15 at 17:24
  • 1
    That matches my expectations so far :). I think you're saying you want to configure multi-seat as per my link above. I think the assumption will be you have separate input devices as well, i.e. there won't be a built-in way to switch the input from one device (keyboard) between the 2 different "seats". – sourcejedi Jun 6 '15 at 21:31
  • 1
    Ah, I guess it's not really possible :(. unix.stackexchange.com/questions/138290/… / help.ubuntu.com/community/MultiseatOneCard – sourcejedi Jun 6 '15 at 22:33

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