asking for help about "acpi_tz0: _CRT value is absurd, ignored (256.0C) "

Chris Whitehouse cwhiteh at
Wed Sep 5 20:08:53 UTC 2012

On 04/09/2012 08:58, chiehhan wrote:
> To whom may concern,
> I am a greenhorn in the field of freebsd.And when I install
> Freebsd9.0 on my laptop HP NX6330,a control spam "acpi_tz0: _CRT
> value is absurd, ignored (256.0C)"occurs.

I created a custom ASL as a workaround.

You can see that I changed the line that says
Return (C316 (0x04, 0x00))
to say
Return (C316 (0x00, 0x02))
which on my laptop gives a temperature of 95C

> I learned some reference about sysctl and revised the configure file
> sysctl.conf,adding two lines below into sysctl.conf:
> hw.acpi.thermal.user_override=1
> hw.acpi.thermal.tz0._CRT=110.0C but
> the control spam remains.

Good try but hw.acpi.thermal.tz0._CRT gets set back to -1

> I read the source code about acpi_thermal.c,but still have no idea
> about how to solve this problem.I am a little desperated and turn
> freebsd-questions at for help.Would you please send me a
> solution?

I think the steps are
1) dump your ASL as per
starting at section 12.17.4 ASL, acpidump, and IASL

2) open your dumped ASL in a plain text editor (vi, joe, ...) and modify 
the value of "Method (_CRT, 0, Serialized)".
shows you some values you can use. Others may work as your ASL is almost 
certainly different from mine.

3) recompile your modified ASL and load it, following section 12.17.4 
ASL, acpidump, and IASL in the handbook.

4) restart your computer and check the value of hw.acpi.thermal.tz0._CRT

If it doesn't work go back to step 2.

YMMV (that means my laptop is running fine several years later but don't 
blame me if yours blows up :) )


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