[SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

Roterodamus · 2025-09-01 18:54:11

Since the most recent kernel update, my Lenovo ThinkPad X240 is not displaying any output, is unresponsive, and the backlight begins to flicker on and off after the “Triggering uevents” screen.
I was running CachyOS fine, but last week, after the latest kernel update, I encountered this problem for the first time. I tried reinstalling CachyOS; the installation went fine, but it won't boot, and the same problem persists. Now it seems I cannot boot into the latest ArchISO again, facing the same issue: a black screen and backlight flickering.

Last edited by Roterodamus (2025-09-06 13:05:48)

topcat01 · 2025-09-01 18:56:15

You can try nomodeset as a kernel parameter in the ISO. There might be a regression. Does the LTS kernel also have a problem?

Roterodamus · 2025-09-01 21:30:43

The ISO booted with nomodeset, but the LTS kernel has the same problem, strangely.
I also had to add the cloud-init=disabled parameter to the ISO because, for some reason, it tries to run at boot and stalls. ???
For a quick sanity check, I installed Fedora Workstation, which runs fine on kernel 6.16.3.

Update: I also tested last months Arch ISO and it boots fine with kernel 6.15.8. I find it strange that LTS does not work at 6.12.44.

Last edited by Roterodamus (2025-09-01 22:24:22)

seth · 2025-09-02 07:32:19

Bugs sometimes and increasingly more often get backported into the LTS tree.
Most likely this is PSR or other power saving related.

I also had to add the cloud-init=disabled parameter to the ISO because

What iso exactly (url) are you booting there?

Can you get us a journal from the flickering system?

sudo journalctl -b | curl -F 'file=@-' 0x0.st

nl6720 · 2025-09-02 11:12:50

seth wrote:

I also had to add the cloud-init=disabled parameter to the ISO because
What iso exactly (url) are you booting there?

The official ISO supports cloud-init. Something in the network is passing cloud-init configuration making it run. Using cloud-init=disabled is the correct way to disable it.

Roterodamus · 2025-09-02 13:57:49

Thanks for looking at this!

I've connected a monitor and was able to get a journal.

http://0x0.st/KHFL.txt

I'm using the ArchISO from the magnet link on the official download page. Not that it's a big problem, but I wonder what triggers cloud-init to run on a 12-year-old laptop not connected to a network. It did the same on last months ISO.

seth · 2025-09-02 14:44:46

i915 on Haswell (only), try to add "i915.enable_psr=0" to the kernel parameters - and, though I'm notyet convinced that actually does anything, you can also try "module_blacklist=simpledrm"

Roterodamus · 2025-09-02 15:06:03

I've tried with both kernel parameters individually and in combination; however, the problem continues to persist.

topcat01 · 2025-09-02 18:10:20

I would probably install the system with an older kernel so it's bootable, and then attempt a bisection, if nothing else works.

seth · 2025-09-02 19:14:28

There's https://bbs.archlinux.org/viewtopic.php?id=307614 (but I'm not sure whether this is really relevant since the relevant patches addressed XE and this is also on Arc)
Does hitting the backlight keys change anything?

Though from the symptoms it sounds like something™ is trying to set an unsupported modeline.
Is this the 1366x768 or 1920x1080 version?
https://www.kernel.org/doc/Documentation/fb/modedb.rst

For further testing (I agree w/ topcat01 and would suggest to immediately test the LTS kernel), do you have an external monitor you could attach?

Roterodamus · 2025-09-05 23:25:43

I have installed version 6.16.5 from testing, and it appears to have fixed the issue for now.

Arch Linux

#1 2025-09-01 18:54:11

[SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

#2 2025-09-01 18:56:15

Re: [SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

#3 2025-09-01 21:30:43

Re: [SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

#4 2025-09-02 07:32:19

Re: [SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

#5 2025-09-02 11:12:50

Re: [SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

#6 2025-09-02 13:57:49

Re: [SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

#7 2025-09-02 14:44:46

Re: [SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

#8 2025-09-02 15:06:03

Re: [SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

#9 2025-09-02 18:10:20

Re: [SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

#10 2025-09-02 19:14:28

Re: [SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

#11 2025-09-05 23:25:43

Re: [SOLVED] Newest arch iso wont boot. Black screen & backlight flicker,

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