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I am trying a triplehead configuration. I already have two monitors working perfectly, but the adapter one is just green. I've done a bunch of things trying to get it to work:

  1. Created a udev rule

    jon@ubuntu: cat /etc/udev/rules.d/70-persistent-displaylink.rules
    # This rule will not work gracefully if more than one USB DisplayLink adapter is present
    # KERNEL=="fb[0-9]*", ATTR{name}=="udlfb", SYMLINK+="usbvideocard"
    KERNEL=="fb1", ATTR{name}=="udlfb", SYMLINK+="usbvideocard"
    

Which creates /dev/usbvideocard pointing to /dev/fb1

  1. Installed xserver-xorg-video-displaylink

  2. Added a modprobe file

    jon@ubuntu: cat /etc/modprobe.d/50-displaylink.conf                   
    options udlfb fb_defio=1
    
  3. Built xf-video-udlfb, which put displaylink_drv.la and displaylink_drv.so into /usr/local/lib/xorg/modules/drivers

  4. Edited Xorg.conf

    Section "Device"
        Identifier      "intel"
        driver          "intel"
    EndSection
    
    Section "Device"
        Identifier      "dl0"
        driver          "fbdev"
        Option  "fbdev" "/dev/usbvideocard"
        Option "ShadowFB" "off"
    EndSection
    
    Section "Monitor"
        Identifier "monitor0"
    EndSection
    
    Section "Monitor"
        Identifier "monitor1"
    EndSection
    
    Section "Monitor"
        Identifier "monitor2"
    EndSection
    
    Section "Screen"
        Identifier "screen0"
        Device "intel"
        Monitor "monitor1"
    EndSection
    
    Section "Screen"
        Identifier "screen1"
        Device "intel"
        Monitor "monitor2"
    EndSection
    
    Section "Screen"
        Identifier "screen2"
        Device "dl0"
        Monitor "monitor0"
        Depth 16
        SubSection "Display"
            Depth     16
            Modes     "1280x1024"
        EndSubSection
    EndSection
    
    Section "Files"
        ModulePath "/usr/local/lib/xorg/modules"
    EndSection
    
    Section "ServerLayout"
        Identifier     "multihead"
        Screen      0  "screen2" 0 0
        Screen      1  "screen1" RightOf "screen0"
        Screen      2  "screen0" RightOf "screen1"
    EndSection
    

I had this working for a little while, then something happened and it broke again. It's really driving me nuts.

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1 Answer 1

I just got done dealing with that particular problem. I have a solution for you to try. The first is to switch your "driver "fbdev" " to "driver "displaylink" ". Unless you really want to use the fbdev driver, the displaylink seems to work better for me. Other than that, I had to force all mine to be the same depth in order to consistently work but I am using Xinerama as well. I just got done looking through my .conf file and it looks almost similar to yours. And I am using both my screens right now. So good luck.

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