stone bobcat Jul 29, 2025, 1:46 PM

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System Information

fastfetch

OS: Arch Linux x86_64
Host: B550M K (-CF)
Kernel: Linux 6.15.8-arch1-1
Uptime: 24 mins
Packages: 1534 (pacman), 10 (flatpak)
Shell: zsh 5.9
Display (VG27AQL1A): 2560x1440 @ 170 Hz in 27" [External] (NOTE: Connected via DisplayPort)
DE: KDE Plasma 6.4.3
WM: KWin (Wayland)
CPU: AMD Ryzen 5 5600X
GPU: AMD Radeon RX 7800 XT [Discrete]
Memory: 64GB total

Install information

Displ. Mgr: SDDM
Bootloader: systemd-boot
Did not use archinstall script (followed wiki)

bootloader configuration (/boot/loader/entries/arch.conf)

title   Arch Linux
linux   /vmlinuz-linux
initrd  /amd-ucode.img
initrd  /initramfs-linux.img
options root=UUID=c98c129a-402a-4f60-9dfa-82375c7e1e3c rw amdgpu.dc=1

Changes from defaults:

Added amdgpu.dc=1 after default options flags (ChatGPT states that because a screen is off, displays recieve no initialisation even if they're turned on after the fact. This flag is supposed to force my system to initialise a display anyway)

Repositories:

pacman only has 'core' and 'extra' enabled.
-# stated this, as there are reports of unstable repositories leading to issues like these, where bugs can possibly cause issues like these to occur

Issue:

If a display is connected to my desktop, but it is not turned on before I start my computer, I have to hard restart my device in order to get a display output from SDDM. Otherwise, I can interact with the computer (numlock works, caps lock work) but I get no display output.

Tried:

Installing AMD microcode (sudo pacman -S amd-ucode)
Using a different keyboard and mouse to wake up my computer
Several restarts
Changing systemd-boot 'options' entry to include 'amdgpu.dc=1' under the options line of /boot/loader/entries/arch.conf
Issue is present whether I do a soft or hard reset.

Thank you in advance for your support. I hope this is enough information to help.

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<-- Please resize your window using the closest bar to the left of this message if you are having trouble viewing this thread on Discord Desktop. Otherwise, if you are on mobile, unfortunatly I cannot make it any more readable until Discord includes collapsable sections of messages.

pearl shale Jul 29, 2025, 1:55 PM

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Try linux-lts

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maybe this is a bug introduced in the newest kernel version

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and send the output of lspci -k | grep -iA3 vga

stone bobcat Jul 29, 2025, 2:05 PM

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pearl shale and send the output of `lspci -k | grep -iA3 vga`

I'll try linux-lts in that case, then I'll send over the output for this command

stone bobcat Jul 29, 2025, 2:12 PM

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pearl shale and send the output of `lspci -k | grep -iA3 vga`

Thank you for your support so far.

Switching to linux-lts does not seem to resolve the issue.

As asked, here is the output of lspci -k | grep -iA3 vga

        Subsystem: Sapphire Technology Limited Device 475d
        Kernel driver in use: amdgpu
        Kernel modules: amdgpu```

dry lakeBOT Jul 29, 2025, 2:12 PM

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thebashforkbomb received a thank you cookie!

stone bobcat Jul 29, 2025, 2:12 PM

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I can verify that Arch is using the kernel through fastfetch

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pearl shale Jul 29, 2025, 2:15 PM

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pretty sure you need the radeon module too

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open /etc/mkinitcpio.conf in a text editor

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and in the MODULES=()

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make it amdgpu radeon

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so, MODULES=(amdgpu radeon)

stone bobcat Jul 29, 2025, 2:16 PM

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I assume you meant /etc/mkinitcpio.conf?
Double checking in case 'mkinicpio.conf' is a thing

stone bobcat Jul 29, 2025, 2:16 PM

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pearl shale so, `MODULES=(amdgpu radeon)`

Thanks

dry lakeBOT Jul 29, 2025, 2:16 PM

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You're thanking too much ó_ò

pearl shale Jul 29, 2025, 2:16 PM

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oh yeah mispelling

stone bobcat Jul 29, 2025, 2:17 PM

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lol real

pearl shale Jul 29, 2025, 2:17 PM

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pearl shale so, `MODULES=(amdgpu radeon)`

because i have THE EXACT SAME THING and it's... fine

stone bobcat Jul 29, 2025, 2:17 PM

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Made the change, so I will reboot and let you know how things go!

pearl shale Jul 29, 2025, 2:17 PM

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WAIT!!!

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@stone bobcat don't reboot yet, you need to rebuild initcpio

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sudo mkinitcpio -S autodetect

stone bobcat Jul 29, 2025, 2:18 PM

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pearl shale <@990624127301869640> don't reboot yet, you need to rebuild initcpio

Oof, thank you for letting me know

dry lakeBOT Jul 29, 2025, 2:18 PM

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You're thanking too much ó_ò

stone bobcat Jul 29, 2025, 2:18 PM

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Sorry about that

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My bad entirely

pearl shale Jul 29, 2025, 2:19 PM

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stone bobcat Made the change, so I will reboot and let you know how things go!

there's a period. you're not supposed to have a period </3

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oops

stone bobcat Jul 29, 2025, 2:19 PM

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pearl shale make it `amdgpu radeon`

Sorry, saw this and thought

pearl shale Jul 29, 2025, 2:19 PM

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because i edited it out in another message

stone bobcat Jul 29, 2025, 2:20 PM

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pearl shale `sudo mkinitcpio -S autodetect`

👍 fixed config and ran this

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Now attempt a reboot?

pearl shale Jul 29, 2025, 2:20 PM

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alr now you can reboot

stone bobcat Jul 29, 2025, 2:20 PM

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This is so embarrassing empty

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I am so sorry

pearl shale Jul 29, 2025, 2:21 PM

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stone bobcat This is so embarrassing <:empty:904500974767452192>

i make mistakes a lot too don't worry

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spellinh**[sic]** mistakes included

stone bobcat Jul 29, 2025, 2:22 PM

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FEK
it still doesnt work

Interesting behaviour however. I can log in by blindly entering my logon password

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Monitor gets a display and everything.

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Might this be an SDDM configuration bug?

pearl shale Jul 29, 2025, 2:22 PM

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stone bobcat Might this be an SDDM configuration bug?

might be. try logging out and then pressing ctrl + alt + F2

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(switches TTY)

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if there's something, then it's probably SDDM

stone bobcat Jul 29, 2025, 2:23 PM

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If I can access a TTY with a display output from my graphics card, then yeah, I agree

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Kinda sucks that I’m having an issue like this when I have an all AMD system

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TTY is accessible! But no signal if I go back to SDDM

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I am currently logged in as my main account via TTY

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From TTY, running startplasma-wayland works

pearl shale Jul 29, 2025, 2:29 PM

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stone bobcat TTY is accessible! But no signal if I go back to SDDM

Welp

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SDDM issue

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Maybe you should try a different login manager?

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I personally use greetd

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.aw Login Managers

halcyon saddleBOT Jul 29, 2025, 2:30 PM

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pearl shale .aw Login Managers

No results found.

pearl shale Jul 29, 2025, 2:30 PM

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.aw LM

halcyon saddleBOT Jul 29, 2025, 2:30 PM

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pearl shale .aw LM

Lm Sensors

https://wiki.archlinux.org/title/Lm_Sensors

pearl shale Jul 29, 2025, 2:30 PM

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halcyon saddle

no </3

stone bobcat Jul 29, 2025, 2:30 PM

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ahah

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I'll give greetd a chance

pearl shale Jul 29, 2025, 2:30 PM

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.aw Display Manager

halcyon saddleBOT Jul 29, 2025, 2:30 PM

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pearl shale .aw Display Manager

Display Manager

https://wiki.archlinux.org/title/Display_Manager

pearl shale Jul 29, 2025, 2:30 PM

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got it right

stone bobcat Jul 29, 2025, 2:31 PM

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First time, too

pearl shale Jul 29, 2025, 2:32 PM

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when you will set it up and it will work, you can

halcyon saddleBOT Jul 29, 2025, 2:32 PM

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Too few arguments for command addnote!
Usage: .addnote <name> <text>

pearl shale Jul 29, 2025, 2:32 PM

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... solved

halcyon saddleBOT Jul 29, 2025, 2:32 PM

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#17640 📣 If there is nothing else that we can do for you, please close this thread by adding "[SOLVED]" to the title.

You can do this on desktop by clicking the three dots on the top right of the page, and pressing "Edit Post".
You can also do this on Android / iOS by long tapping your post in the text channel list, and tapping "Edit Post".

Your title should be like so: https://media.discordapp.net/attachments/1377138685538992252/1394893287667667035/image.png?ex=6878771b&is=6877259b&hm=e490049052812fd977384de338fa0f0c0634c50ed75a6f5a00bc7c7a847ff278&=&format=webp&quality=lossless&width=628&height=122
Thank you

stone bobcat Jul 29, 2025, 2:34 PM

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Thanks! I know the drill - I read up before consulting for help
-# I hope it shows lmao
Thank you for your assistance as well. It is greatly appreciated

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[SOLVED] SDDM does not autodetect monitors after initialisation.

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Issue appears to be a bug with SDDM, as using another greeter completely resolves the issue.
Kudos to @pearl shale for the support.

#[SOLVED] SDDM does not autodetect monitors after initialisation. Switching greeter fixes it

System Information

fastfetch

Install information

bootloader configuration (/boot/loader/entries/arch.conf)

Changes from defaults:

Repositories:

Issue:

Tried: