Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753805AbXLKRDD (ORCPT ); Tue, 11 Dec 2007 12:03:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755915AbXLKRCY (ORCPT ); Tue, 11 Dec 2007 12:02:24 -0500 Received: from terminus.zytor.com ([198.137.202.10]:58449 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755901AbXLKRCW (ORCPT ); Tue, 11 Dec 2007 12:02:22 -0500 Message-ID: <475EC24E.4070900@zytor.com> Date: Tue, 11 Dec 2007 09:01:02 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Rene Herman CC: David Newall , Krzysztof Halasa , 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> <475E341F.9000107@keyaccess.nl> In-Reply-To: <475E341F.9000107@keyaccess.nl> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 827 Lines: 23 Rene Herman wrote: > On 11-12-07 02:25, H. Peter Anvin wrote: > >> David Newall wrote: >>> Where did the 8us delay come from? The documentation and source is >>> careful not to say how long the delay is. Would changing it to, say >>> 1us, be technically wrong? Is code that requires 8us correct? >> >> I think a single ISA bus transaction is 1 ?s, so two of them back to >> back should be 2 ?s, not 8 ?s... > > Sigh. And now where do these _two_ transactions come from? (and yes, see > Alan's folowups, a transaction on a spec bus is 1 us). > Stale memory, sorry. -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/