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Amit Dube avatar Ubuntu

No virtual display when using modesetting in Ubuntu 20.04(xrandr: Configure crtc 3 failed)

mo flag
Amit Dube

I have two graphic cards in my laptop(os: Ubuntu 20.04).

$ lspci | grep VGA    
>> 00:02.0 VGA compatible controller: Intel Corporation UHD Graphics (rev 05)
>> 01:00.0 VGA compatible controller: NVIDIA Corporation Device 1f95 (rev a1)

I have enabled Nvidia prime in NVIDIA on-demand mode. enter image description here

The /etc/X11/xorg.conf file looks like this

section "Device"
    Identifier      "intel"
    Driver          "modesetting"
    BusID           "PCI:0:2:0"
EndSection

And I added 20-intel.conf in /usr/share/X11/xorg.conf.d/ with following contents.

Section "Device"
    Identifier "intelgpu0"
    Driver "intel"
    Option "VirtualHeads" "2"
    Option "TearFree" "true"
EndSection

After rebooting I ran the following commands

xrandr --addmode VIRTUAL1 1920x1080
xrandr --output VIRTUAL1 --mode 1920x1080 --left-of eDP1

After that I was able to create virtual display. But the graphics was fuzzy & videos in vlc wouldn't play or started lagging.

After changing the driver to modesetting in 20-intel.conf

Section "Device"
        Identifier "intelgpu0"
        Driver "modesetting"
        Option "VirtualHeads" "2"
        Option "TearFree" "true"
EndSection

The fuzzy graphics issue was solved. But I can't create the virtual display using the above xrandr commands I get the following error

xrandr: Configure crtc 3 failed.
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blusser avatar Ubuntu
tm flag
blusser

currently I am trying to get the VIRTUAL1 Runnung as well and I think I found your answer: https://github.com/kbumsik/VirtScreen/issues/16

create: sudo vim /usr/share/X11/xorg.conf.d/30-virtscreen.conf with the content:

`# nvidia/nouveau/amdgpu device should be configured first before Intel GPU
Section "Device"
    Identifier "nvidiagpu0"
    Driver     "nvidia" # Because you are using Nvidia proprietary driver. Change to "nouveau" if you are using open source nouveau driver
EndSection
# Then configure intel internal GPU
Section "Device"
    Identifier "intelgpu0"
    Driver     "intel"
    # You may put Option "VirtualHeads" "1" here but it seem you don't need to put this for Ubuntu 18.04.
EndSection`

if you delete your 20-intel.conf you should be golden. CHEERS

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Amit Dube avatar
mo flag
Amit Dube
I've already tried this solution before posting this question here. This doesn't work for me. I get a black screen after ubuntu boots up.
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blusser avatar
tm flag
blusser
I think this is because your default graficsdriver is modesetting. I had the same issue aswell. If you disable it, or plug in a HDMI cable and restart your displaymanager it changes to intel and nvidia and then i could use it
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blusser avatar
tm flag
blusser
You can verivy this by booting without hdmi or vga plugged in, just your laptop and then enter `inxi -G` and compare the output with when it is plugged in. The folowing is a link to configuration with modesetting: I haven't tried it though. You could tell me if it worked, if you tried it. https://unix.stackexchange.com/questions/585069/unable-to-add-a-virtual-display-to-xorg/585078#585078
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