RFE: console_blank_hook that calls userspace helper

[Eugene Pavlovsky <heilong@bluebottle.com>]

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http://bugzilla.kernel.org/show_bug.cgi?id=4767:

Bugzilla Bug 4767 	RFE: console_blank_hook that can call userspace
program
Submitter:   	heilong@bluebottle.com (Eugene Pavlovsky)

I think it'd be very good to have a console_blank_hook handler that
would call a
userspace program/script/generate hotplug event whatever. Currently,
the console
can only be blanked using APM, so no options exist for people using
ACPI. I've
got a Radeon graphics chip on my laptop, and the LCD backlight can be
controlled
(on/off) using radeontool. If there was a userspace callback
interface
to
console blanking, I would just make a callback script that calls
"radeontool
light off" on blank and "radeontool light on" on unblank - really
easy. I think
this userspace console_blank_hook handler is very simple to put into
kernel, but
I'm not a kernel developer myself, so wouldn't risk sending any
patches (that
call system("some_script")), because I probably won't make things as
they should
be in the kernel.


------- Additional Comment #1 From Eugene Pavlovsky 2005-06-29 06:46
-------

Created an attachment (id=5238)
implemented this functionality in a kernel module

I've actually checked the kernel sources on how this can be done and
implemented the proposed functionality in a kernel module. The module
attaches
a console blank hook function that uses kernel's
call_usermodehelper()
to
execute /sbin/user_vc_blank (defined at compile-time) to
blank/unblank
the
console. I've written a sample script (which I use on my laptop) that
uses
radeontool to turn the LCD backlight off/on. Maybe this functionality
should be
moved to the kernel. On the other hand, as it still needs userspace
utilities,
maybe it's better off as a module. Anyway, please give it a thought,
or at
least made this module available.


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