From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id CC3076B003D for ; Sat, 21 Feb 2009 22:13:59 -0500 (EST) Message-ID: <49A0C2D4.20009@zytor.com> Date: Sat, 21 Feb 2009 19:13:24 -0800 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: [PATCH] kmemcheck: disable fast string operations on P4 CPUs References: <1235223364-2097-1-git-send-email-vegard.nossum@gmail.com> <1235223364-2097-2-git-send-email-vegard.nossum@gmail.com> In-Reply-To: <1235223364-2097-2-git-send-email-vegard.nossum@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Vegard Nossum Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ingo Molnar , Pekka Enberg List-ID: Vegard Nossum wrote: > This patch may allow us to remove the REP emulation code from > kmemcheck. > +#ifdef CONFIG_KMEMCHECK > + /* > + * P4s have a "fast strings" feature which causes single- > + * stepping REP instructions to only generate a #DB on > + * cache-line boundaries. > + * > + * Ingo Molnar reported a Pentium D (model 6) and a Xeon > + * (model 2) with the same problem. > + */ > + if (c->x86 == 15) { If this is supposed to refer to the Intel P4 core, you should exclude the post-P4 cores that also have x86 == 15 (e.g. Core 2 and Core i7). If those are affected, too, they should be mentioned in the comment. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org