Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262886AbUDAM3U (ORCPT ); Thu, 1 Apr 2004 07:29:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262887AbUDAM3U (ORCPT ); Thu, 1 Apr 2004 07:29:20 -0500 Received: from jurand.ds.pg.gda.pl ([153.19.208.2]:62637 "EHLO jurand.ds.pg.gda.pl") by vger.kernel.org with ESMTP id S262886AbUDAM3N (ORCPT ); Thu, 1 Apr 2004 07:29:13 -0500 Date: Thu, 1 Apr 2004 14:29:12 +0200 (CEST) From: "Maciej W. Rozycki" To: Jamie Lokier Cc: Bill Davidsen , Len Brown , 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: <20040331150219.GC18990@mail.shareable.org> Message-ID: References: <4069A359.7040908@nortelnetworks.com> <1080668673.989.106.camel@dhcppc4> <4069D3D2.2020402@tmr.com> <20040331150219.GC18990@mail.shareable.org> 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: 1045 Lines: 26 On Wed, 31 Mar 2004, Jamie Lokier wrote: > > Well, "cmpxchg", "xadd", etc. can be easily emulated with an aid of a > > spinlock. With SMP operation included. > > Nope. Len Brown wrote: > > > Linux uses this locking mechanism to coordinate shared access > > to hardware registers with embedded controllers, > > which is true also on uniprocessors too. > > You can't do that with a spinlock. The embedded controllers would > need to know about the spinlock. Hmm, does it mean we support x86 systems where an iomem resource has to be atomically accessible by a CPU and a peripheral controller? -- + 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/