Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261728AbUDBKyK (ORCPT ); Fri, 2 Apr 2004 05:54:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261931AbUDBKyK (ORCPT ); Fri, 2 Apr 2004 05:54:10 -0500 Received: from jurand.ds.pg.gda.pl ([153.19.208.2]:5074 "EHLO jurand.ds.pg.gda.pl") by vger.kernel.org with ESMTP id S261728AbUDBKyH (ORCPT ); Fri, 2 Apr 2004 05:54:07 -0500 Date: Fri, 2 Apr 2004 12:54:06 +0200 (CEST) From: "Maciej W. Rozycki" To: Len Brown Cc: Jamie Lokier , Bill Davidsen , Chris Friesen , Willy Tarreau , "Richard B. Johnson" , Alan Cox , Arkadiusz Miskiewicz , Marcelo Tosatti , Linux Kernel Mailing List , ACPI Developers Subject: Re: [ACPI] Re: Linux 2.4.26-rc1 (cmpxchg vs 80386 build) In-Reply-To: <1080852371.30349.19.camel@dhcppc4> Message-ID: References: <4069A359.7040908@nortelnetworks.com> <1080668673.989.106.camel@dhcppc4> <4069D3D2.2020402@tmr.com> <20040331150219.GC18990@mail.shareable.org> <1080852371.30349.19.camel@dhcppc4> Organization: Technical University of Gdansk MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 973 Lines: 21 On Thu, 1 Apr 2004, Len Brown wrote: > ACPI specifies a location in regular memory that is used to contain the > lock. The lock is used both by the CPU and by the embedded controller > to cover access to shared registers. We don't spin on this lock because > we don't know how long the embedded controller might hold it. Instead > when we fail to acquire it we schedule an event to trigger when the lock > is free. OK, that's clear to me now. Then does this lock really require "cmpxchg"? Wouldn't a lone "xchg" suffice? -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available + - 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/