From owner-freebsd-acpi@FreeBSD.ORG Tue Jul 10 08:46:06 2012 Return-Path: Delivered-To: freebsd-acpi@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 638F5106564A for ; Tue, 10 Jul 2012 08:46:06 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from citadel.icyb.net.ua (citadel.icyb.net.ua [212.40.38.140]) by mx1.freebsd.org (Postfix) with ESMTP id B13048FC18 for ; Tue, 10 Jul 2012 08:46:05 +0000 (UTC) Received: from porto.starpoint.kiev.ua (porto-e.starpoint.kiev.ua [212.40.38.100]) by citadel.icyb.net.ua (8.8.8p3/ICyb-2.3exp) with ESMTP id LAA16837; Tue, 10 Jul 2012 11:46:01 +0300 (EEST) (envelope-from avg@FreeBSD.org) Received: from localhost ([127.0.0.1]) by porto.starpoint.kiev.ua with esmtp (Exim 4.34 (FreeBSD)) id 1SoW52-000OMQ-JV; Tue, 10 Jul 2012 11:46:00 +0300 Message-ID: <4FFBEBC8.2090309@FreeBSD.org> Date: Tue, 10 Jul 2012 11:46:00 +0300 From: Andriy Gapon User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:13.0) Gecko/20120620 Thunderbird/13.0.1 MIME-Version: 1.0 To: Nate Lawson References: <4FF94EC4.1060109@FreeBSD.org> <023CA42F-C5FD-4F67-AD70-84DE68B3FBA8@root.org> In-Reply-To: <023CA42F-C5FD-4F67-AD70-84DE68B3FBA8@root.org> X-Enigmail-Version: 1.4.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "freebsd-acpi@freebsd.org" Subject: Re: disabled CST_CNT write X-BeenThere: freebsd-acpi@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: ACPI and power management development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Jul 2012 08:46:06 -0000 on 08/07/2012 19:49 Nate Lawson said the following: > On Jul 8, 2012, at 2:11 AM, Andriy Gapon wrote: > >> acpi_cpu.c has a block of code to write CST_CNT to SMI_CMD, but the block is >> under #ifdef notyet. It seems that the code was added that many years ago and >> never enabled. >> Now, judging from the reports I've seen on this mailing list, it appears that >> _CST changes do happen and the driver seem to handle them sufficiently well. >> I think that a lot of modern platforms do not even provide CST_CNT and assume >> that an OS is able to handle C-state change notifications. >> So, I guess that it should be safe to enable the code in question now. >> >> Could anyone with a FreeBSD laptop and non-zero CST_CNT in FADT please test this? > > It was only under an #ifdef because at the time our CST implementation couldn't handle CST changes cleanly. I had added some support for it, but since it couldn't be tested, I wasn't sure how actual hardware would behave. > > I think it's fine to enable now. I think 2007-era Thinkpads were some of the first to add this feature. Nate, thank you for the information/explanation. -- Andriy Gapon