[patch] enhance powerd(8) to handle max temperature

[Doug Ambrisko]

Bill Moran writes:
| In response to "Dag-Erling Sm?rgrav" <des at des.no>:
| > Hajimu UMEMOTO <ume at freebsd.org> writes:
| > > I cannot see _TC1, _TC2 nor _TSP in your `acpidump -dt' output.
| > > Further, there is no _PSV definition in anywhere, in the first place.
| > > It seems to me that your ACPI BIOS doesn't support passive cooling at
| > > all.
| > 
| > Going off on a tangent, I too have several motherboards (965P-based)
| > which do not define any ACPI thermal zones, which leads me to wonder:
| > what is the preferred way to access thermal data these days?  IPMI?  Do
| > we have IPMI support in base or ports?
| 
| Not sure about the base, but we've been using ipmitool from ports for
| a while with success, and we're investigating FreeIPMI.

Both ipmitool and freeipmi in ports can use the ipmi(4) which lives in 
the base system on 6.X & above.  I recommend to use ipmi(4) versus
direct HW access from user-land so things are a bit more orderely.
So it is a mix of base and ports.  I like ipmitool & freeipmi in ports
as they have a bunch of people working on IPMI things and adding
features.  Personally, I went with ipmitool since some Dell people
are contributors to it.

Not all systems have IPMI but it tends to be nice when they do.  There
are several things that have IPMI as a subset.  Things that might have
it could have ASF(AMD) or AMT (Intel) capable machines.  Some times
it an add-in daughter card on server type motherboard.  With AMT it
seems Intel is pushing it more into the Desktop space :-)

Now with regards to CPU temperature.  Newer Intel CPU's do not report
their temperature.   I have read that they report how many degrees
away until there is a problem but I think that might have been a joke.

Systems that have IPMI version 2 are nice since that means they are 
supposed to support Serial Over Lan (SOL) via the standard :-)

Doug A.