Date: Tue, 14 Sep 2010 09:06:55 -0700 From: Nate Lawson <nate@root.org> To: Andriy Gapon <avg@freebsd.org> Cc: Alexander Motin <mav@freebsd.org>, freebsd-acpi@freebsd.org Subject: Re: CPU C-state storange on Panasonic TOUGH BOOK CF-R9 Message-ID: <4C8F9D9F.4080704@root.org> In-Reply-To: <4C8F35FD.2090603@freebsd.org> References: <4C8BCAC5.5050008@root.org> <mailpost.1284277196.1767764.83548.mailing.freebsd.current@FreeBSD.cs.nctu.edu.tw> <4C8C8B64.8020907@FreeBSD.org> <20100912182625.c49d3f1d.nork@FreeBSD.org> <4C8C9F06.4090505@icyb.net.ua> <20100912190537.621e357e.nork@FreeBSD.org> <20100912190952.8c0d5726.nork@FreeBSD.org> <20100912192518.e791c191.nork@FreeBSD.org> <4C8CAC01.70004@icyb.net.ua> <4C8CAD7D.50602@FreeBSD.org> <4C8CF03F.1050902@icyb.net.ua> <4C8CF412.9080601@icyb.net.ua> <4C8CF91A.4040804@FreeBSD.org> <4C8E5A5D.6000303@icyb.net.ua> <4C8F35FD.2090603@freebsd.org>
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Andriy Gapon wrote: > on 13/09/2010 20:07 Andriy Gapon said the following: >> I am also going to take a look how Linux and OpenSolaris name the C-states. > > Well, Linux does what you suggested, it uses index of a C-state as its name. > There is one difference from our current code - if a C-state is skipped for some > reason, then its index is not re-used, but the entry is marked as non-valid. > So, if we skip "C2" for some reason, then "C3" will become "C2". Not so on Linux. > Also, they print a type/class of a C state using C1, C2, C3 and "--" for > higher/unknown types. > > Additionally, it seems that we do not currently have any support for Functional > Fixed Hardware (FFH) way of providing C states. In this case _CST returns GAS > of a register used to enter a C state with address space ID set to > ACPI_ADR_SPACE_FIXED_HARDWARE (0x7f/127). Such addresses should be handled in a > special way: > ftp://download.intel.com/technology/IAPC/acpi/downloads/30222305.pdf > > Currently we simply (and silently) ignore such _CST entries. > I think that this should be useful (if not necessary) with mwait. I added some FFHW support for ACPI P-states. You can see that in the cpufreq code or in the speedstep driver. -- Nate
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