Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754291AbXLKBwY (ORCPT ); Mon, 10 Dec 2007 20:52:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752159AbXLKBwP (ORCPT ); Mon, 10 Dec 2007 20:52:15 -0500 Received: from terminus.zytor.com ([198.137.202.10]:60522 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752092AbXLKBwO (ORCPT ); Mon, 10 Dec 2007 20:52:14 -0500 Message-ID: <475DED16.8020103@zytor.com> Date: Mon, 10 Dec 2007 17:51:18 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: David Newall CC: Krzysztof Halasa , Rene Herman , Pavel Machek , Andi Kleen , Alan Cox , "David P. Reed" , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar Subject: Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops References: <475879CD.9080006@reed.com> <20071207160439.71b7f46a@the-village.bc.nu> <20071209125458.GB4381@ucw.cz> <20071209165908.GA15910@one.firstfloor.org> <20071209212513.GC24284@elf.ucw.cz> <475CBDD7.5050602@keyaccess.nl> <475DE37F.20706@davidnewall.com> <475DE6F4.80702@zytor.com> <475DEB23.1000304@davidnewall.com> In-Reply-To: <475DEB23.1000304@davidnewall.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 999 Lines: 21 David Newall wrote: > > Exactly. You think it's 2us, but the documentation doesn't say. The _p > functions are generic inasmuch as they provide an unspecified delay. > Drivers which work across platforms, and which use _p, therefore have > different delays on different platforms. Should the length of the delay > be unimportant? I wouldn't have thought so. If it is important, does > that mean that such drivers are buggy on some platforms? > That the _p delay is different across platforms is actually to be expected, since it pretty much amounts to a platform delay. And yes, if it is used as a specific walltime delay that has nothing to do with the bus architecture of the system then I would classify that as a driver bug. -hpa -- 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/