Date: Fri, 24 Jun 2005 01:06:53 -0000 From: "Alexandre \"Sunny\" Kovalenko" <Alex.Kovalenko@verizon.net> To: Nate Lawson <nate@root.org> Cc: freebsd-acpi@freebsd.org, Matthew Flanagan <flanagan.matt@gmail.com> Subject: Re: Changing temperature threshold Message-ID: <1130461569.1345.6.camel@RabbitsDen> In-Reply-To: <42BB28BD.5080202@root.org> References: <7cd06a2d05062205331d03372c@mail.gmail.com> <7cd06a2d050623073452e3c3f9@mail.gmail.com> <1130426516.777.7.camel@RabbitsDen> <42BB28BD.5080202@root.org>
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On Thu, 2005-06-23 at 14:25 -0700, Nate Lawson wrote:
> Alexandre "Sunny" Kovalenko wrote:
> >>When I try to raise hw.acpi.thermal.tz0._CRT to 85C (which is the
> >>threshold in the BIOS setup) it doesn't work:
> >>
> >>bell# sysctl hw.acpi.thermal.tz0._CRT=3580 # 3580 tenths of Kelvin=85C
> >>sysctl: oid 'hw.acpi.thermal.tz0._CRT' is read only
> >>
> >>Now, my question is: how do I change this value? I've read several
> >>manpages (acpi(4), acpi_thermal(4), acpiconf(8), loader(8), and many
> >>others) and checked the handbook, to no avail. Can anyone point me
> >>to the right direction?
> >
> > One of the ways to deal with that would be to dump your ASL (see
> > Handbook for guidance), find lines which look like:
> > Method (_CRT, 0, NotSerialized)
> > {
> > Return (KELV (0x5d))
> > }
> > modify them to your liking, compile ASL and override it during boot
> > (instructions on how to compile and override are in Handbook as well).
> > Please, note that actual value returned is in the 1/10th of the degree
> > of Kelvin. Function KELV above has following ASL code associated with
> > it:
> > Method (KELV, 1, NotSerialized)
> > {
> > Store (Arg0, Local1)
> > Multiply (0x0A, Local1, Local1)
> > Add (Local1, 0x0AAC, Local1)
> > Return (Local1)
> > }
> > Thermal management chapter of the ACPI specification should provide you
> > with ample explanation of what this is all about.
>
> This explanation is correct. The reason why the sysctl is read-only is
> because the values are supplied by the BIOS and are what the OEM thinks
> are critical temperatures. However, we need a way to allow override in
> the case of obviously wrong values like this. I'll probably change it
> to allow overriding from the loader but be read-only in sysctl to avoid
> accidental changes from users experimenting.
>
Would you consider making ACx levels writeable while you are at that? It
will make it much easier to implement thermal hysteresis from userland.
--
Alexandre "Sunny" Kovalenko (Олександр Коваленко)
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