acpi_tz0: _CRT value is absurd, ignored (256.0C) (was pr kern/105537)

[Ian Smith]

On Tue, 24 Mar 2009, Pasi Parviainen wrote:
 > Chris Whitehouse wrote:
 > > Hi, I sent this a while ago but don't think there was a reply. I'm about to
 > > embark on a custom ASL to load in loader.conf as per
 > > http://www.freebsd.org/doc/en/books/handbook/acpi-debug.html but just
 > > wondering if their might be a 'proper' fix on the way. I do have the latest
 > > bios installed.
 > 
 > Loading custom ASL with modified _CRT value for temperature zone in
 > question will solve the problem, see below for more information.
 > 
 > > Would it help if I installed 8-CURRENT?
 > 
 > Probably not, see below.
 > 
 > > -------- Original Message --------
 > > Subject: pr kern/105537
 > > Date: Mon, 12 Jan 2009 15:00:49 +0000
 > > From: Chris Whitehouse <cwhiteh at onetel.com>
 > > To: freebsd-acpi at FreeBSD.org
 > > 
 > > hi,
 > > 
 > > Please would you cc me in any reply as I'm not subscribed, thanks.
 > > 
 > > I have the same problem noted in
 > > 
 > > http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/105537
 > > 
 > > of frequent messages saying
 > > 
 > > acpi_tz0: _CRT value is absurd, ignored (256.0C)
 > > 
 > > on my HP nc6320 laptop, model RH383ET.
 > > 
 > 
 > I have HP 6510b and HP 2510p laptops and had same problem with those.
 > Actual problem is that the ACPI thermal code in kernel does sanity-check
 > for temperature values, and accepts only values between 0 - 200 Celsius.
 > To solve the problem you either create custom DSDT which returns 200.0C
 > value instead of 256.0C for thermal zone in question or increase the limit of
 > the sanity-check code of ACPI thermal code (src/sys/dev/acpica/acpi_thermal.c
 > function: acpi_tz_sanity).
 > 
 > Proper way to solve this in my opinion is to increase the range of
 > sanity-check function from 0 - 200 Celsius to 0 - 256 Celsius, or at
 > least provide sysctl variable to disable thermal sanity-checks.

Even 200C is absurd, really.  That's above the melting point of many 
types of solder (http://www.rfcafe.com/references/electrical/solder.htm) 
while 256C exceeds the melting point of _most_ types of solder.  I seem 
to recall that this limit used to be 150C, still hotter than anything 
you actually want to have anywhere on a computer board.

No sense checking sanity to then accept insane values; fix the broken 
ASL.  256 sounds suspiciously like a byte-swapped value, perhaps?

cheers, Ian