Arch Linux

toljaga

Member

Registered: 2021-10-30

Posts: 12

[SOLVED] Trying to use laptop as additional monitor on KDE

Hi,
I'm sure this has been done a million times before, but I've spent the better part of today trying to get this to work and it just won't.

The idea is simple, I have three displays on my desk. Two of them are regular monitors connected to my desktop computer, one of them is my laptop's integrated display.
I would like to configure it such that it feels like I have three monitors. That means I want nothing running on my laptop (other than the minimum required to display the image sent over the network) and everything running on my desktop. I want to be able to drag windows and copy-paste as though you would on a normal triple monitor setup.

Both of the devices are running Arch and KDE (I've also tried a couple of other DEs and WMs on the laptop to no avail).

I don't care whether I use wayland or x11, I just want it to work on KDE (which supports both). I've tried both routes and here are some "results":

Wayland:
Wayland is frustrating because KDE uses the KWin compositor, which in turn is not wlroots based and does not support this type of thing natively (so, no wayvnc). There is a KDE tool for this, krfb-virtualmonitor, which works, but it is very poorly documented and, most importantly, seems to be locked at a very low framerate (regardless of the resolution or compression I specify: it's the same framerate when I use lossless native resolution of 1366x768 or JPEG-ified-beyond-recognition 320x200 grayscale), which makes me think that it's not an encoding/decoding/bandwith issue, but just hardcoded somewhere. I would like to see at least 24fps (even if compressed or low-res) which I should have the bandwith for (there is 1Gbps between these two).

X:
On X, I can't even get this to work. Moreover, I am stumped because, having googled around for quite a bit, people seem to recommend using x2x. I looked into this, and x2x works, but it only shares the keyboard and mouse to the already running desktop on the laptop. That's not what I want. I don't know why people mention it when people want to achieve what I'm trying to, maybe I'm an idiot and set it up wrong, but it doesn't seem to me that it does what I want. I also tried x2vnc, the description of which roughly matches what I'm trying to set up, but it's such an ancient (relatively) piece of software that it's not packaged on arch, not even in the AUR (except for a broken alternative version that doesn't compile), and I need to patch it to build from source. Even after patching it into compiling it doesn't work at all, albeit it shows some signs of life (namely messing with my mouse).

Thanks for any clues in advance.

Last edited by toljaga (2024-07-22 13:08:35)

Lone_Wolf

Administrator

From: Netherlands, Europe

Registered: 2005-10-04

Posts: 12,824

Re: [SOLVED] Trying to use laptop as additional monitor on KDE

Have you tried x11vnc ?

https://askubuntu.com/questions/1464323 … oth-are-ru shows how to setup that for 2 ubuntu systems and may be helpful .

X or wayland :
wayland lacks protocols to do these things, stick to X .

---

Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.

clean chroot building not flexible enough ?
Try clean chroot manager by graysky

toljaga

Member

Registered: 2021-10-30

Posts: 12

Re: [SOLVED] Trying to use laptop as additional monitor on KDE

Hi,

x11vnc worked using the guide in the link you provided. It's not wonderful (~18-20 ish fps, and I do realize they aren't entire frames) but probably as good as it's going to get. It's visibly better than the Wayland concoction I cobbled together, but not by that much.

Thanks.