From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030298Ab2AFKV5 (ORCPT ); Fri, 6 Jan 2012 05:21:57 -0500 Received: from nat28.tlf.novell.com ([130.57.49.28]:50198 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030200Ab2AFKVy convert rfc822-to-8bit (ORCPT ); Fri, 6 Jan 2012 05:21:54 -0500 Message-Id: <4F06AF4A020000780006AC14@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.0 Date: Fri, 06 Jan 2012 07:22:34 +0000 From: "Jan Beulich" To: "Andi Kleen" , "H. Peter Anvin" Cc: , , Subject: Re: x86-64: memset()/memcpy() not fully standards compliant References: <4F05BBFE020000780006A983@nat28.tlf.novell.com> <20120105182846.GQ11715@one.firstfloor.org> <4F0630CC.7050001@zytor.com> <20120106014748.GS11715@one.firstfloor.org> <4F06566B.8080708@zytor.com> In-Reply-To: <4F06566B.8080708@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> On 06.01.12 at 03:03, "H. Peter Anvin" wrote: > On 01/05/2012 05:47 PM, Andi Kleen wrote: >>> >>> Is that still true, and do we even use string instructions still on >>> those old CPUs? Jan's fixes don't introduce any additional delays in >>> the non-string-instruction paths. >> >> Yes various of the CPUs with bugs used string instructions. >> > > Which CPUs are you talking about here? Indeed, I went through various specification updates/revision guides without finding any relevant erratum. >> >> Both string and non string instructions are used on modern CPUs, >> so making any of that slower is not a good idea. >> > > Obviously not, but I'm perfectly fine turning REP_GOOD off on old broken > CPUs. Yes, that's what my plan would have been too, had I been able to identify any specific CPU(s) that actually suffer from such problems. Jan