Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269040AbUJQDo4 (ORCPT ); Sat, 16 Oct 2004 23:44:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269048AbUJQDo4 (ORCPT ); Sat, 16 Oct 2004 23:44:56 -0400 Received: from mustang.oldcity.dca.net ([216.158.38.3]:16596 "HELO mustang.oldcity.dca.net") by vger.kernel.org with SMTP id S269049AbUJQDoI (ORCPT ); Sat, 16 Oct 2004 23:44:08 -0400 Subject: Re: High pitched noise from laptop: processor.c in linux 2.6 From: Lee Revell To: Alan Cox Cc: Pavel Machek , M , Linux Kernel Mailing List In-Reply-To: <1097979705.13269.9.camel@localhost.localdomain> References: <41650CAF.1040901@unimail.com.au> <20041007103210.GA32260@atrey.karlin.mff.cuni.cz> <20041007143245.GA1698@openzaurus.ucw.cz> <1097956343.2148.17.camel@krustophenia.net> <1097963167.13226.4.camel@localhost.localdomain> <1097976283.2148.34.camel@krustophenia.net> <1097979705.13269.9.camel@localhost.localdomain> Content-Type: text/plain Message-Id: <1097984002.2148.44.camel@krustophenia.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Sat, 16 Oct 2004 23:33:23 -0400 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1138 Lines: 28 On Sat, 2004-10-16 at 22:21, Alan Cox wrote: > On Sul, 2004-10-17 at 02:24, Lee Revell wrote: > > > And heavily reduced accuracy on a lot of laptops where 1000Hz > > > is enough to make the clock slide every time the battery state is > > > queried or an SMM event triggers. > > Wouldn't such a laptop be horribly broken? 1ms is a LONG time to > > disable interrupts. That's millions of CPU cycles... > > Yes, and most laptops have this problem. They use SMM traps to talk to > the battery including huge delay loops and during those SMM traps no > interrupt code runs. > Ugh! I was under the impression that mostly older machines had this problem and it was a minority of laptops. I could not find a lot of info on SMM - several of the links I found were DDJ "Undocumented Corner" articles. Anyway this explains probably half the weird bug reports on the linux audio user list. Lee - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/