Multihead through VNC

Seacat17 · 2025-07-02 23:32:23

I've spent like a several hours researching this stuff already and now I'm gonna ask for help because I have no idea how to do this.

I have two laptops. One is cool, one is janky. The cool laptop is my main computer that I use for everything, but it has an obvious disadvantage that is a disadvantage of all the laptops. It has only one screen, and this creates loads of problems when doing stuff like livestreaming.

However, no matter how janky the second laptop is, it has a 1366x768 LCD. I wish I could use this second laptop as a second monitor over LAN with something like VNC. I know, it sounds horrible but I cannot afford buying a second monitor so I'm trying to work with what I have on my hands already.

This is where problems begin.

All the guides I've looked through expect me to have some kind of "spare" output, like an unused VGA, HDMI or DP. However, in this computer I only have ONE HDMI, and it is DISABLED manually since I restrict my NVidia GPU from running Xorg because of a driver bug discussed here: https://github.com/doitsujin/dxvk/issues/4503

This means that I only have one working output, and it is my main built-in screen.

I've spent like... 3 hours at this point trying to create a virtual output for Xorg, using dummy drivers and virtual monitors. However, when I try to do that I get one of two things: either the Xorg REFUSES to run at all after configuration and reports not being able to find any screens, or Xorg runs fine but xrandr reports no additional outputs.

Can somebody please guide my dumb butt through this process? I swear, I've tried my best but I'm stuck.

EDIT: Writing posts while emotional is NEVER a good idea.

Xorg runs on AMD iGPU here. Not Intel, not Nvidia. AMD.

Last edited by Seacat17 (2025-07-02 23:38:09)

dakota · 2025-07-03 01:43:38

I'm not sure I understand.

Are you saying...

1. You want to use the cool laptop as your main computer?
2. You want the janky laptop to be able to connect to the cool laptop and display different windows?

How about this?

1. Run vncserver on the cool laptop
2. Connect to the cool laptop (across your local network) through tigervnc

Would something like that work?

Cheers,

Seacat17 · 2025-07-03 06:12:40

dakota wrote:

I'm not sure I understand.
Are you saying...
1. You want to use the cool laptop as your main computer?
2. You want the janky laptop to be able to connect to the cool laptop and display different windows?
How about this?
1. Run vncserver on the cool laptop
2. Connect to the cool laptop (across your local network) through tigervnc
Would something like that work?
Cheers,

I want to use my janky laptop as a second monitor over LAN. I've tried the vncserver solution but this requires me to use 2 laptops at once. Not what I need.

Last edited by Seacat17 (2025-07-03 06:15:32)

seth · 2025-07-03 08:13:32

All the guides I've looked through

Does that include https://wiki.archlinux.org/title/Extreme_Multihead#VNC ?

Seacat17 · 2025-07-03 09:00:20

seth wrote:

All the guides I've looked through
Does that include https://wiki.archlinux.org/title/Extreme_Multihead#VNC ?

Of course. I'm dumb but not THAT dumb to not look in the wiki before asking.

Last edited by Seacat17 (2025-07-03 09:00:39)

seth · 2025-07-03 15:59:37

The wiki lists multiple approaches, which one are you currently attempting and what do your config files and your xorg log look like?

Seacat17 · 2025-07-03 20:26:56

seth wrote:

The wiki lists multiple approaches, which one are you currently attempting and what do your config files and your xorg log look like?

I attempted the one that mentions dummy driver. When I reach my computer today I'll try evdi.

seth · 2025-07-03 20:32:41

the wiki wrote:

It is in principle possible to set up a dummy device alongside a real device by adding a dummy device and xinerama configuration to xorg. It is tricky to have this configuration working properly, and it is not ideal for laptops, as you will not be able to hotplug monitors

=> https://wiki.archlinux.org/title/Extrem … DMI_output

Seacat17 · 2025-07-03 21:04:01

seth wrote:

=> https://wiki.archlinux.org/title/Extrem … DMI_output

Seacat17 wrote:

However, in this computer I only have ONE HDMI, and it is DISABLED manually since I restrict my NVidia GPU from running Xorg because of a driver bug discussed here: https://github.com/doitsujin/dxvk/issues/4503

Seacat17 · 2025-07-03 21:16:48

Here is my Xorg configuration file.

https://termbin.com/6sme

Keep in mind that I removed all the alterations that caused it not to boot.

Last edited by Seacat17 (2025-07-03 21:17:10)

seth · 2025-07-03 21:56:46

On topic:

xrandr -q

(there's gonna be some unused output, it doesn't have to be a HDMI one…)

semi-offtopic:
You're hiding the nvidia GPU from the server but are still offloading?
Do you instead get away w/

Option "UseDisplayDevice" "none"

https://download.nvidia.com/XFree86/Lin … tions.html
?
Also

	Identifier  "Card0"
	Driver      "amdgpu"

have you actually tested this problem w/ the modesetting driver?

Keep in mind that I removed all the alterations that caused it not to boot.

Option "Monitor-Virtual-1" "Monitor1"

This is nonsense.

Section "InputDevice"
	Identifier  "Keyboard0"
	Driver      "kbd"
EndSection

Section "InputDevice"
	Identifier  "Mouse0"
	Driver      "mouse"
	Option	    "Protocol" "auto"
	Option	    "Device" "/dev/input/mice"
	Option	    "ZAxisMapping" "4 5 6 7"
EndSection

these device drivers don't exist since decades

	Screen      0  "Screen0" 0 0
	Screen      1  "Screen1" RightOf "Screen0"

You intend to be able to move windows among outputs, right?
https://wiki.archlinux.org/title/Multih … te_screens
Don't.

Section "Files"
Section "Module"

skip those…

If you're not interested in arranging outputs and having per-monitor maximized/fullscreen windows AND there's really no free output you could just extend the root window outside the boundaries of your local monitor and share that part via vnc…

Seacat17 · 2025-07-03 22:06:33

[seacat17@seacat17-laptop ~]$ xrandr -q
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384
eDP connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 194mm
   1920x1080     60.00*+  40.00  
   1680x1050     60.00  
   1280x1024     60.00  
   1440x900      60.00  
   1280x800      60.00  
   1280x720      60.00  
   1024x768      60.00  
   800x600       60.00  
   640x480       60.00  
[seacat17@seacat17-laptop ~]$

I am trying evdi right now and I already had some success. I am still tinkering though.

Seacat17 · 2025-07-14 19:30:48

So basically, I've done this. I used EVDI, x11VNC (NOT RECOMMENDED, I use RustDesk now) and xrandr. I will probably fill out that wiki page about how to do this correctly.

Arch Linux

#1 2025-07-02 23:32:23

Multihead through VNC

#2 2025-07-03 01:43:38

Re: Multihead through VNC

#3 2025-07-03 06:12:40

Re: Multihead through VNC

#4 2025-07-03 08:13:32

Re: Multihead through VNC

#5 2025-07-03 09:00:20

Re: Multihead through VNC

#6 2025-07-03 15:59:37

Re: Multihead through VNC

#7 2025-07-03 20:26:56

Re: Multihead through VNC

#8 2025-07-03 20:32:41

Re: Multihead through VNC

#9 2025-07-03 21:04:01

Re: Multihead through VNC

#10 2025-07-03 21:16:48

Re: Multihead through VNC

#11 2025-07-03 21:56:46

Re: Multihead through VNC

#12 2025-07-03 22:06:33

Re: Multihead through VNC

#13 2025-07-14 19:30:48

Re: Multihead through VNC

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