Can't start X: "intel(0): Failed to set backlight acpi_video0"

Nebu · 2014-08-17 04:09:45

Hi guys,

I was trying to adjust my laptop brightness, and after running some commands in the terminal, the brightness ended up too high for me to see anything, so I rebooted the laptop. Since then, I haven't been able to run x via `startx`. Here's what I believe to be the relevant lines from logs:

(EE) intel(0): Failed to set backlight acpi_video0 for output LVDS1 to brightness level 0, disabling
(EE)
(EE) Backtrace:
(EE) 0: /usr/bin/Xorg.bin (xorg_backtrace+0x52) [0x81de282]
(EE) 1: /usr/bin/Xorg.bin (0x8048000+0x19a502) [0x81e2502]
(EE) 2: linux-gate.so.1 (__kernel_rt_sigreturn+0x0) [0xb7792d34]
...

(Sorry if there are typos in the above, I had to retype them as I write this post here on my desktop, since I'm not sure how to do much with my laptop without X running).

If it helps any, here's the bash_history I have which records what commands I was running while trying to adjust my brightness settings:

cd /sys/class/backlight/
ls
cd acpi_video0
ls
less max_brightness
tee brightness <<< 5
sudo tee brightness <<< 5
sudo tee brightness <<< 1
sudo tee brightness <<< 0
sudo tee brightness <<< 10
sudo tee brightness <<< 1
yaourt calise
yaourt redshift
redshift
yaourt xcalib
man xcalib
xcalib --help
xcalib
xcalib -co 40 -a
xcalib -co 100 -a
xcalib -co 250 -a
xcalib -co 100 -a
xcalib -b 100 -a
xcalib -b 99 -a
xcalib -b 995

In my /sys/class/backlight directory, I have acpi_video0, acpi_video1, intel_backlight and radeon_bl1. Right now, the brightness file in each has the following content (as determined by, e.g., cat /sys/class/backlight/acpi_video0/brightness):

acpi_video0: 10
acpi_video1: 1
intel_backlight: 4422465
radeon_bl1: 255

Last edited by Nebu (2014-08-17 17:10:45)

Nebu · 2014-08-17 04:22:15

Probably relevant:

I noticed that if I run startx as another user (e.g. root), X will start just fine.

So then I tried renaming my .xinitrc file to .xinitrc.bak, and again X started fine.

Then I tried having a completely empty .xinitrc file (by running `touch .xinitrc`). This time X will segfault with the above error again.

Then I tried copying the .xinitrc file from /etc/skel/.xinitrc to my home directory. Again, X segfaults with the above error.

So it seems like if I don't have an .xinitrc file, X can start up. But if I have an .xinitrc file, including an empty one or a "default" one, X will segfault.

ewaller · 2014-08-17 04:55:51

Is your system fully up to date? I always worry when I see yaourt go by. I trust it not.

Try doing a sudo pacman -Syu and see what happens.

<moderatorMode> And please use bbcode code tags when posting output. The same link is below every post box on the fourms. I would appreciate it if you would update your first post. Thanks. </moderatorMode>

Last edited by ewaller (2014-08-17 04:58:07)

Nebu · 2014-08-17 17:12:49

Well, Arch is a rolling release, so the system is "never" up to date, but I ran pacman -Syu, accepted all the updates, and re-ran startx and got the same error as above.

ewaller · 2014-08-17 17:31:55

Thank you for updating your post. By up to date, I wanted to ensure you had not tried partial updates. Yaourt makes it simple to break your system that way.

Nebu · 2014-08-17 17:41:43

ewaller wrote:

Thank you for updating your post.

No problem.

ewaller wrote:

By up to date, I wanted to ensure you had not tried partial updates. Yaourt makes it simple to break your system that way.

Since X seems to work fine when I don't have an xinitrc file, I think the problem must be related to a configuration setting persisted somewhere (e.g. somewhere it's remembering that I had set brightness to 0, I guess, and so when it tries to "restore" that configuration setting, X segfaults). However, I can't figure out where it's storing this setting, since the problem is still happening even with a blank xinitrc file, or with a default xinitrc file. I was hoping somebody knew the logic of where X looks for various settings when it finds an xinitrc file in your home directory.

ewaller · 2014-08-17 18:30:41

I just tried with an existing, but empty ~/.xinitrc file. I did not see a segfault, but X did exit immediately.

Nebu · 2014-08-17 18:36:14

What about with the default ~/.xinitrc file, as copied from /etc/skel/.xinitrc?

Kolt Penny · 2014-08-28 05:23:52

Funny. I get the same "intel(0): Failed to set backlight acpi_video0" error in my log file, but x runs without problem from the default files in xorg.conf.d.

However, I did have to manually install twm, xclock, xterm, xf86-input-mouse, xf86-input-keyboard and xf86-input-synaptics before everything started working.

Nebu · 2014-08-28 06:13:40

I filed a bug with X, you can read about it at https://bugs.freedesktop.org/show_bug.cgi?id=82833

Arch Linux

#1 2014-08-17 04:09:45

Can't start X: "intel(0): Failed to set backlight acpi_video0"

#2 2014-08-17 04:22:15

Re: Can't start X: "intel(0): Failed to set backlight acpi_video0"

#3 2014-08-17 04:55:51

Re: Can't start X: "intel(0): Failed to set backlight acpi_video0"

#4 2014-08-17 17:12:49

Re: Can't start X: "intel(0): Failed to set backlight acpi_video0"

#5 2014-08-17 17:31:55

Re: Can't start X: "intel(0): Failed to set backlight acpi_video0"

#6 2014-08-17 17:41:43

Re: Can't start X: "intel(0): Failed to set backlight acpi_video0"

#7 2014-08-17 18:30:41

Re: Can't start X: "intel(0): Failed to set backlight acpi_video0"

#8 2014-08-17 18:36:14

Re: Can't start X: "intel(0): Failed to set backlight acpi_video0"

#9 2014-08-28 05:23:52

Re: Can't start X: "intel(0): Failed to set backlight acpi_video0"

#10 2014-08-28 06:13:40

Re: Can't start X: "intel(0): Failed to set backlight acpi_video0"

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