[patch] acpi_battery -- notify critical 'life' via devd(8)

[Pietro Cerutti]

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Hi Nate, list,

pre-everything:
	my knowledge of the ACPI subsystem is very limited,
	as is my understanding of general kernel mechanisms.
	--> if this patch is crap, please be patient with me :)

reason:
	I want my laptop to notify me when the battery life
	reaches a certain critical low level (say, 5%).

solution:
	I've implemented a kernel process in acpi_battery which
	notifies devd(8) when the critical level is reached.
	For this, I've added the following sysctl OIDs to the
	hw.acpi.battery tree:
	polling_rate:	in seconds, self explaining...
	critical_level:	in percent, also self explaining...

questions:
	I've chosen a notify of 0x80 for this event. The reason
	just being that I've seen acpi_thermal starting its own
	notify values with this number.
	Is there any guidelines for Notify values?

devd:
	This patch allows for a devd.conf(5) entry such as:
	notify 10 {
	    match "system"      "ACPI";
	    match "subsystem"   "Battery";
	    match "notify"      "0x80";
	    action "logger -p kern.emerg 'WARNING: low battery!'";
	};

the patch:
	http://gahr.ch/FreeBSD/patches/_pending/acpi_battery.c.diff

Any comments, tests, bug-reports, ... welcome!

Thanks!

P.S. please CC me as I don't follow freebsd-acpi@ (yet).$

- --
Pietro Cerutti
gahr at FreeBSD.org

PGP Public Key:
http://gahr.ch/pgp

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