Arch Linux

Deamon_DS

Member

From: Netherlands

Registered: 2021-08-06

Posts: 2

Xrandr not detecting any monitors [SOLVED]

Hey I am joining Arch linux on my main PC to now and want to use a double monitor set up. But when I start up my pc no monitors are detected. Xrandr gives me the following output: xrandr:
-------------------------------------------------------------------------------------------------------------
| Failed to get size of gamma for output default                                                       |
| Screen 0: minimum 1920 x 1080, current 1920 x 1080, maximum 1920 x 1080   |
| default connected primary 1920x1080+0+0 0mm x 0mm                                      |
| 1920x1080      0.00*                                                                                               |
-------------------------------------------------------------------------------------------------------------

The output is from the within the WM bspwm. If I exit bspwm and enter it again. Xrandr detects everthing like it should. I made a file under /etc/lightdm/display_setup.sh filled with the following code:
---------------------------------------------------------------------------------
| #!/bin/bash                                                                               |
| xrandr --setprovideroutputsource modesetting NVIDIA-0        |
| xrandr --auto                                                                            |
| xrandr --output "DP-0" --auto --output "DP-3" --left-of "DP-0"  |
----------------------------------------------------------------------------------
This file is called by lighdm under /etc/lightdm/lightdm.conf on the line : display-setup-script=/etc/lightdm/display_setup.sh

(not sure if it is needed but)
My hardware is the following:
  - RTX 3060TI
  - AMD RYZEN 7 5800X
  - MSI X470 gaming plus max

I think the GPU isn't yet initialized. But I also used the command : GRUB_CMDLINE_LINUX_DEFAULT="quiut splash rcutree.rcu_idle_gp_delay=1" in the Grub file.
I am not sure what to do to fix the problem.

To be exact the problem is that xrandr is not detecting any monitor on initial startup of the pc.

BTW I am sorry I don't know how to make the boxes for code in this form.

Last edited by Deamon_DS (2021-08-08 10:06:26)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,224

Re: Xrandr not detecting any monitors [SOLVED]

For code tags, see https://bbs.archlinux.org/help.php#bbcode

Do the monitors come up correctly on lightdm startup itself? Generally that the GPU isn't yet initialized is something that can happen in which case you'll want to https://wiki.archlinux.org/title/NVIDIA … de_setting set that kernel parameter and add the mentioned modules to your initramfs/mkinitcpio config.

Also this lightdm display setup script is normally only relevant for laptops/hybrid graphics in that form, but this doesn't appear to be a laptop?

Deamon_DS

Member

From: Netherlands

Registered: 2021-08-06

Posts: 2

Re: Xrandr not detecting any monitors [SOLVED]

Thanks it works now.

Thanks a lot mate.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,224

Re: Xrandr not detecting any monitors [SOLVED]

Great, please mark as [SOLVED] by editing the title in your first post.