Re: removing an envsys temperature limit

["Constantine A. Murenin" <cnst%NetBSD.org@localhost>]

On 29 February 2016 at 04:18, Julian Coleman <jdc%coris.org.uk@localhost> wrote:
> Hi,
>
>> Do they persist between the reboots and cold boots?  Or does CritMax
>> change back to 54degC at certain times?
>
> I'd say that in general "it depends".  If the chip is reset, it will go
> back to its default values.  If the machine firmware writes its settings
> on every boot, then you will see the firmware values instead.  Cold boot
> or power-on will almost certainly result in the firmware values being
> written.  Warm boot or reboot might not - I have seen the values that I
> set in a previous boot being retained across reboot.

True that!

>
> However, when NetBSD runs, we don't check to see if it's a cold or warm
> start, so we should assume that the "wrong" values have been set by the
> hardware.

This is where the above analysis is incorrect — 54degC is not a
‘"wrong" value’.  It's a correct value that, once exceeded, would
ensure that all fans run at full speed (the chip takes care of that
automatically, even if the whole OS is frozen or some such, take a
look at the specs at
http://www.onsemi.com/pub_link/Collateral/ADM1027-D.PDF).

What's "wrong" is, (0), these values from the chip are all marked as
CRIT, instead of WARN, by dbcool, and, (1), powerd doing an
unconditional shutdown, whereas, (2), dbcool might as well not be the
only driver out of touch in regards to (0) having such an effect on
(1).

Cheers,
Constantine.SU.