xrandr: where does VIRTUAL1 output come from?

Question

Executing xrandr shows me the outputs my graphics card has, but also a VIRTUAL1 one:

$ xrandr
Screen 0: minimum 8 x 8, current 4160 x 1024, maximum 32767 x 32767
eDP1 connected 1600x900+0+0 (normal left inverted right x axis y axis) 309mm x 174mm
   1600x900       60.0*+
   1440x900       59.9
...
DP2 disconnected (normal left inverted right x axis y axis)
DP2-1 connected primary 1280x1024+1600+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1280x1024      60.0*+   60.0* 
   1024x768       60.0  
...
VIRTUAL1 connected (normal left inverted right x axis y axis)
   1024x768       60.0  
VIRTUAL2 disconnected (normal left inverted right x axis y axis)

Where does the VIRTUAL1 come from? Who creates it? How can I remove it?

This is an intel graphics card. Do other drivers support virtual outputs, too?

Answer 1

To my knowledge, VIRTUAL1 is created automatically, or when I undock my laptop from dock with additional screen still turned on. For some reason, X11 keeps all my apps on virtual desktop which I don't actually see (but I can still move a mouse there). I noticed that my secondary display (DP2) was disconnected, but still initialized:

[lzap@lzapx ~]$ xrandr
Screen 0: minimum 8 x 8, current 4160 x 1440, maximum 32767 x 32767
LVDS1 connected 1600x900+2560+0 (normal left inverted right x axis y axis) 309mm x 174mm
   1600x900      60.01*+  40.00  
   1368x768      60.00  
   1280x720      60.00  
   1024x768      60.00  
   1024x576      60.00  
   960x540       60.00  
   800x600       60.32    56.25  
   864x486       60.00  
   800x450       60.00  
   640x480       59.94  
   720x405       60.00  
   640x360       60.00  
DP1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected 2560x1440+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
DP3 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
HDMI3 disconnected (normal left inverted right x axis y axis)
VGA1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
  2560x1440 (0x109) 241.500MHz
        h: width  2560 start 2608 end 2640 total 2720 skew    0 clock  88.79KHz
        v: height 1440 start 1442 end 1476 total 1481           clock  59.95Hz

After I switched it off, the virtual screen also disappeared and all my apps moved to the laptop display:

[lzap@lzapx ~]$ xrandr --output DP2 --off
[lzap@lzapx ~]$ xrandr
Screen 0: minimum 8 x 8, current 1600 x 900, maximum 32767 x 32767
LVDS1 connected 1600x900+0+0 (normal left inverted right x axis y axis) 309mm x 174mm
   1600x900      60.01*+  40.00  
   1368x768      60.00  
   1280x720      60.00  
   1024x768      60.00  
   1024x576      60.00  
   960x540       60.00  
   800x600       60.32    56.25  
   864x486       60.00  
   800x450       60.00  
   640x480       59.94  
   720x405       60.00  
   640x360       60.00  
DP1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
DP3 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
HDMI3 disconnected (normal left inverted right x axis y axis)
VGA1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

This is Thinkpad laptop with Intel Graphics (i7 chip) and HP LCD screen, no virtual environment or NVidia card or anything like that.

Answer 2

Where does the VIRTUAL1 come from? Who creates it? How can I remove it?

Quite a few different things could configure this; it's just a virtual device. It can be used as a part of nVidia Optimus configuration, VMWare configuration, or something done to fix a resolution issue in another application you have installed. I believe there are cases where it can show up live like that when an external monitor has been disconnected but the system is still using it.

There's no way to know, in this context, when or why it was originally set up.

This is an intel graphics card. Do other drivers support virtual outputs, too?

Yes. The virtual display isn't a feature of the driver; it's part of X11.

Answer 3

For me, it comes from the packet xserver-xorg-video-dummy

see https://askubuntu.com/questions/453109/add-fake-display-when-no-monitor-is-plugged-in