From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: Re: [patch 6/8] hwmon driver for ACPI 4.0 power meters Date: Wed, 24 Nov 2010 23:36:35 +0000 Message-ID: <20101124233635.GB12372@srcf.ucam.org> References: <200909181941.n8IJf91g002548@imap1.linux-foundation.org> <20101124213936.GA9829@srcf.ucam.org> <20101124232159.GX14383@tux1.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from cavan.codon.org.uk ([93.93.128.6]:51626 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752272Ab0KXXgy (ORCPT ); Wed, 24 Nov 2010 18:36:54 -0500 Content-Disposition: inline In-Reply-To: <20101124232159.GX14383@tux1.beaverton.ibm.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Darrick J. Wong" Cc: akpm@linux-foundation.org, lenb@kernel.org, linux-acpi@vger.kernel.org, pavel@ucw.cz, rui.zhang@intel.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