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Date:      Tue, 28 Jun 2011 15:14:34 -0400
From:      Jung-uk Kim <jkim@FreeBSD.org>
To:        freebsd-acpi@FreeBSD.org
Cc:        Vitaly Magerya <vmagerya@gmail.com>, Andriy Gapon <avg@freebsd.org>
Subject:   Re: (Missing) power states of an Atom N455-based netbook
Message-ID:  <201106281514.36324.jkim@FreeBSD.org>
In-Reply-To: <4E09BADF.7050702@FreeBSD.org>
References:  <BANLkTim%2B1UwquMJ32WP8wZBGkYxPv78MLA@mail.gmail.com> <BANLkTikmVUtLyANBSqYb%2BL-xkwQ4Zo51Eg@mail.gmail.com> <4E09BADF.7050702@FreeBSD.org>

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On Tuesday 28 June 2011 07:28 am, Andriy Gapon wrote:
> I think that part (but not all) of the differences between FreeBSD
> and Linux can be explained by the fact that FreeBSD currently
> doesn't advertise itself as featuring ACPI_CAP_SMP_C1_NATIVE and
> ACPI_CAP_SMP_C3_NATIVE.  I am not sure what it would take to
> actually support these features.  I think that Linux does support
> (or at least advertise support) for these features.

Yes, Linux supports this Intel-specific feature.  I think it shouldn't 
be too hard for us, however.  We just have to add support for 
Intel-specific _CST FFH (Functional Fixed Hardware) in 
sys/dev/acpica/acpi_cpu.c.  You can find more information from "Intel 
Processor Vendor-Specific ACPI" (order number 302223-005) on Intel 
website.  Also, arch/x86/kernel/acpi/cstate.c of Linux source may 
help.  I believe Linux actually supports all Intel-specific FFHs, 
BTW.

Jung-uk Kim



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