devd and/or ACPI not reporting a heat problem

M. Warner Losh imp at
Thu Jun 17 16:01:59 UTC 2010

In message: <4C187778.9060909 at>
            Doug Barton <dougb at> writes:
: Howdy,
: I thought my heat problems were over with this laptop thanks to all
: the great suggestions I've received about powerd, no stepping, etc. (I
: also propped up both the back and the front to make a nice big air
: pocket.) I've always been pretty religious about blowing the dust off
: the fans and heat sinks, but I guess it's been dustier than I thought
: lately because I finally "caught" my laptop doing what it's been doing
: for the last 2 weeks, which is (occasionally) powering down when it
: was unattended; and the problem was heat.
: Of course I've been running devd all along, and so I initially ruled
: out the heat problem due to this entry in devd.conf:
: # Notify all users before beginning emergency shutdown when we get
: # a _CRT or _HOT thermal event and we're going to power down the system
: # very soon.
: notify 10 {
:         match "system"          "ACPI";
:         match "subsystem"       "Thermal";
:         match "notify"          "0xcc";
:         action "logger -p kern.emerg 'WARNING: system temperature too high,
:         shutting down soon!'";
: };
: I'm not getting any of those notices in the logs, so I was looking
: other places. (I do get other ACPI-related activity from devd, such as
: the notice that it's going on and off AC power.)
: So, 2-part question, how can I make sure that devd gets the message,
: and how do I make sure that the notice comes _before_ the BIOS forces
: the system to power off. I.e., I'd like to have some sort of devd
: notice that comes in time to do a clean shutdown, or perhaps some
: other mitigation strategy prior to the BIOS taking over.

You may need a simple cron entry that checks the temperature and
report when it is getting close.  acpi should be reporting thermal
events before then that aren't 0xcc, but if not, that's the fallback
that people use.

Sadly, at least for one of my laptops, I've seen sudden 10-20C spikes
which trigger this.  I think this laptop is badly broken, and don't
use it any more.


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