Date: Thu, 23 Jun 2005 14:25:17 -0700 From: Nate Lawson <nate@root.org> To: "Alexandre \"Sunny\" Kovalenko" <Alex.Kovalenko@verizon.net> Cc: freebsd-acpi@freebsd.org, Matthew Flanagan <flanagan.matt@gmail.com> Subject: Re: Changing temperature threshold Message-ID: <42BB28BD.5080202@root.org> In-Reply-To: <1130426516.777.7.camel@RabbitsDen> References: <7cd06a2d05062205331d03372c@mail.gmail.com> <7cd06a2d050623073452e3c3f9@mail.gmail.com> <1130426516.777.7.camel@RabbitsDen>
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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. -- Nate
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