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From: Matthew Garrett <mjg59@srcf.ucam.org>
To: "Darrick J. Wong" <djwong@us.ibm.com>
Cc: akpm@linux-foundation.org, lenb@kernel.org,
	linux-acpi@vger.kernel.org, pavel@ucw.cz, rui.zhang@intel.com
Subject: Re: [patch 6/8] hwmon driver for ACPI 4.0 power meters
Date: Wed, 24 Nov 2010 23:36:35 +0000	[thread overview]
Message-ID: <20101124233635.GB12372@srcf.ucam.org> (raw)
In-Reply-To: <20101124232159.GX14383@tux1.beaverton.ibm.com>

On Wed, Nov 24, 2010 at 03:21:59PM -0800, Darrick J. Wong wrote:

> As I recall, Pavel had an objection that it wasn't clear to him that ACPI
> advertising a capping ability necessarily meant that the platform hardware
> would actually _enforce_ that cap, so I put in a DMI hook so that the cap only
> appears on systems where ACPI advertises the ability /and/ someone can verify
> that it's enforced outside software (either by patching the DMI table or by
> supplying a module parameter).
> 
> I guess we were afraid that someone would build an ACPI power meter and then
> require software to read the cap out of ACPI and enforce it(??) though I can't
> find a link to that discussion.  I'll just attach it below, since the marc.info
> archive of mm-commits doesn't seem to have caught it.

The spec defines bit 2 of the capabilities list as "Power meter supports 
hardware enforced limit" - I don't think we're meant to worry about the 
OS here.

-- 
Matthew Garrett | mjg59@srcf.ucam.org

      reply	other threads:[~2010-11-24 23:36 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-09-18 19:41 [patch 6/8] hwmon driver for ACPI 4.0 power meters akpm
2009-09-18 20:46 ` Darrick J. Wong
2009-09-19  5:32 ` Len Brown
2010-11-24 21:39 ` Matthew Garrett
2010-11-24 23:21   ` Darrick J. Wong
2010-11-24 23:36     ` Matthew Garrett [this message]

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