Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756368AbXLGSsd (ORCPT ); Fri, 7 Dec 2007 13:48:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752612AbXLGSsZ (ORCPT ); Fri, 7 Dec 2007 13:48:25 -0500 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:56260 "EHLO the-village.bc.nu" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753474AbXLGSsY (ORCPT ); Fri, 7 Dec 2007 13:48:24 -0500 Date: Fri, 7 Dec 2007 18:42:37 +0000 From: Alan Cox To: Rene Herman Cc: Andi Kleen , "David P. Reed" , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Subject: Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops Message-ID: <20071207184237.04174f42@the-village.bc.nu> In-Reply-To: <475994C5.7090307@keyaccess.nl> References: <475879CD.9080006@reed.com> <20071207160439.71b7f46a@the-village.bc.nu> <20071207163116.GB5992@one.firstfloor.org> <20071207171957.73b619b1@the-village.bc.nu> <475994C5.7090307@keyaccess.nl> X-Mailer: Claws Mail 2.10.0 (GTK+ 2.10.14; i386-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1050 Lines: 25 On Fri, 07 Dec 2007 19:45:25 +0100 Rene Herman wrote: > On 07-12-07 18:19, Alan Cox wrote: > > > On Fri, 7 Dec 2007 17:31:16 +0100 > > Andi Kleen wrote: > > > >>> You don't need to. Port 0x80 historically is about 8uS so just udelay(8) > >>> and make sure the initial default delay is conservative enough before the > >> How would you make it conservative enough handling let's say a 6Ghz CPU > >> that can execute multiple jumps per cycle? > > > > Pick a sane worst case and go with it at boot. We don't have to be > > accurate before we tune udelay - over long in uSecs isnt going to hurt, > > and most post boot _p's can be replaced by udelay(8) now > > Isn't 8 generally a bit overly long? I believe the norm is 1? 8uS is an ISA bus transaction. -- 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/