Does anyone know which kernel option would be responsible for
/sys/class/backlight/intel_backlight? I've disabled some backlight
stuff in the kernel but the directory still appears. I get screen
backlight control on my laptop if I do:

echo 0 > /sys/class/backlight/intel_backlight/brightness

but if xlockmore blanks my screen, I have to issue the above again
before screen backlight control works again. I also have acpi_video0
in /sys/class/backlight and I think removing intel_backlight might fix
the problem.

I could try deleting the directory. Is that safe? Are the files and
folders in /sys generated dynamically at boot?

- Grant

On Fri, Mar 16, 2012 at 2:14 PM, Grant <emailgrant@gmail.com> wrote:
> Does anyone know which kernel option would be responsible for
> /sys/class/backlight/intel_backlight? *I've disabled some backlight
> stuff in the kernel but the directory still appears. *I get screen
> backlight control on my laptop if I do:
>
> echo 0 > /sys/class/backlight/intel_backlight/brightness
>
> but if xlockmore blanks my screen, I have to issue the above again
> before screen backlight control works again. *I also have acpi_video0
> in /sys/class/backlight and I think removing intel_backlight might fix
> the problem.
>
> I could try deleting the directory. *Is that safe? *Are the files and
> folders in /sys generated dynamically at boot?

The /sys directory is like /proc; it's a virtual directory which
serves as interface to several kernel knobs. I don't think you can
remove any dir from it, and if you do, next boot it will show up
again.

Regards.
--
Canek Peláez Valdés
Posgrado en Ciencia e Ingeniería de la Computación
Universidad Nacional Autónoma de México

On Fri, Mar 16, 2012 at 3:14 PM, Grant <emailgrant@gmail.com> wrote:
> Does anyone know which kernel option would be responsible for
> /sys/class/backlight/intel_backlight? *I've disabled some backlight
> stuff in the kernel but the directory still appears. *I get screen
> backlight control on my laptop if I do:

Probably from the intel video driver (i915 or whatever)

>> Does anyone know which kernel option would be responsible for
>> /sys/class/backlight/intel_backlight? *I've disabled some backlight
>> stuff in the kernel but the directory still appears. *I get screen
>> backlight control on my laptop if I do:
>>
>> echo 0 > /sys/class/backlight/intel_backlight/brightness
>>
>> but if xlockmore blanks my screen, I have to issue the above again
>> before screen backlight control works again. *I also have acpi_video0
>> in /sys/class/backlight and I think removing intel_backlight might fix
>> the problem.
>>
>> I could try deleting the directory. *Is that safe? *Are the files and
>> folders in /sys generated dynamically at boot?
>
> The /sys directory is like /proc; it's a virtual directory which
> serves as interface to several kernel knobs. I don't think you can
> remove any dir from it, and if you do, next boot it will show up
> again.

You're right, "operation not permitted" there.

- Grant

>> Does anyone know which kernel option would be responsible for
>> /sys/class/backlight/intel_backlight? *I've disabled some backlight
>> stuff in the kernel but the directory still appears. *I get screen
>> backlight control on my laptop if I do:
>
> Probably from the intel video driver (i915 or whatever)

Sounds like I won't be able to remove it without removing support for
my video card.

I have to enter 'echo 0 >
/sys/class/backlight/intel_backlight/brightness' again every time
xlockmore comes on. Does anyone know what's going on there?

- Grant

[snip]
> I have to enter 'echo 0 >
> /sys/class/backlight/intel_backlight/brightness' again every time
> xlockmore comes on. *Does anyone know what's going on there?
>
> - Grant

Strangely, this isn't required unless xlockmore has been running for
at least a few minutes. Does it sound like this is induced by
xlockmore behavior or Xorg or something else?

- Grant