Re: dbcool, envsys, powerd shutting down my machine

[Julian Coleman <jdc%coris.org.uk@localhost>]

Hi,

> In general, I personally don't think it ever makes sense to shutdown
> by default when the temperature is exceeded, since most of these
> sensors aren't really all that reliable (especially if you're getting
> them over i2c, with potential bus locking issues and race conditions
> with BIOS / IPMI; getting a bit sidelined, at the very least, the
> sensor values should be dampened, which is what's done in OpenBSD's
> sensorsd, not sure if anything similar is done here).

A lot of sensor chips have a separate hardware alert signals that are
activated if a temperature is outside the limits (either "warning" or
"critical" or both).  Some hardware will shut down without OS intervention
if this signal is asserted.  So, it's good to have the correct values set
to avoid damage, and some hardware enforces that.

I have seen spurious values read from i2c chips, so perhaps it does make
sense to wait for more than one reading that is outside the limit.  Note,
that the sensor chip itself will usually have something similar - for
example waiting until 3 readings are outside the range before activating
the hardware alert.  Not sure if we need dampening, but ignoring spurious
values would be good (although it wouldn't help here).

Regards,

J

-- 
   My other computer runs NetBSD too   -         http://www.netbsd.org/