It looks like VIRTUAL* is not enabled by default on old X11. According to the [Arch Linux Wiki](https://wiki.archlinux.org/index.php/Extreme_Multihead#VNC) you can enable VIRTUAL* by adding the following configuration for X11:

[YaoLiMuMu]

It looks like VIRTUAL* is not enabled by default on old X11. According to the Arch Linux Wiki you can enable VIRTUAL* by adding the following configuration for X11:

Section "Device"
    Identifier "intelgpu0"
    Driver "intel"
    Option "VirtualHeads" "1"
EndSection

Copy/paste the above code in /etc/X11/xorg.conf.d/20-intel.conf or /usr/share/X11/xorg.conf.d/20-intel.conf, and then reboot the system. This tells the Intel driver to create one virtual display, VIRTUAL1. You can change the number "1" in Option "VirtualHeads" "1" to any number to create VIRTUAL1, VIRTUAL2, ... and VIRTUALn (which is unnecessary for VirtScreen use case),

Originally posted by @kbumsik in #16 (comment)

[YaoLiMuMu]

Hi, I did so, but when I reboot ubuntu20 system, there is always a lot of screen tearing, like this

[ductm208]

Hi, I did so, but when I reboot ubuntu20 system, there is always a lot of screen tearing, like this

yes same to me, Lenovo P1 gen 3 dual cards (intel + nvidia quadro)

[pinkpigeonltd]

Linux Mint 20.2, Intel HD 520, Kernel 5.4.0-92 here

I am trying to follow the instructions here:

Using a virtual output

Some drivers, like the old "intel" driver, support virtual displays. In this case, create at-least one virtual display in xorg

/etc/X11/xorg.conf.d/20-intel.conf

Section "Device"
Identifier "intelgpu0"
Driver "intel"
Option "VirtualHeads" "1"
EndSection

The name of the output will normally be VIRTUAL1 (you can check with xrandr without any argument). The virtual display can then be activated using.

$ xrandr --output VIRTUAL1 --mode

I can see VIRTUAL1 when running 'xrandr', however, in the display manager, or other tools it's not shown. Xrandr shows it as 'disconnected'.

I tried 'connecting' it by running xrandr --output VIRTUAL1 --mode<resolution>, but it just says 'cannot find mode'. How do I add a mode to a virtual display?

Edit: I tried adding a mode by using xrandr --addmode VIRTUAL1 1920x1080 and then ```xrandr --output VIRTUAL1 --mode 1920x1080 --right-of eDP1``

But this just corrupts my screen and crashes Cinnamon.