Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262610AbVEMXRX (ORCPT ); Fri, 13 May 2005 19:17:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262483AbVEMXQR (ORCPT ); Fri, 13 May 2005 19:16:17 -0400 Received: from hummeroutlaws.com ([12.161.0.3]:13838 "EHLO atpro.com") by vger.kernel.org with ESMTP id S262481AbVEMXOu (ORCPT ); Fri, 13 May 2005 19:14:50 -0400 Date: Fri, 13 May 2005 19:14:19 -0400 From: Jim Crilly To: "Barry K. Nathan" Cc: "Richard F. Rebel" , Andi Kleen , Gabor MICSKO , linux-kernel@vger.kernel.org Subject: Re: Hyper-Threading Vulnerability Message-ID: <20050513231419.GP27568@mail> Mail-Followup-To: "Barry K. Nathan" , "Richard F. Rebel" , Andi Kleen , Gabor MICSKO , linux-kernel@vger.kernel.org References: <1115963481.1723.3.camel@alderaan.trey.hu> <1116009483.4689.803.camel@rebel.corp.whenu.com> <20050513191443.GN27568@mail> <20050513201840.GB7436@ip68-225-251-162.oc.oc.cox.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050513201840.GB7436@ip68-225-251-162.oc.oc.cox.net> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1297 Lines: 31 On 05/13/05 01:18:40PM -0700, Barry K. Nathan wrote: > On Fri, May 13, 2005 at 03:14:43PM -0400, Jim Crilly wrote: > > And what if you have more than one physical HT processor? AFAIK there's no > > way to disable HT and still run SMP at the same time. > > Actually, there is; read my post earlier in this thread: > http://marc.theaimsgroup.com/?l=linux-kernel&m=111598859708620&w=2 > > To elaborate on the "check dmesg" part of that e-mail: > > After you reboot with "maxcpus=2" (or however many physical CPU's you > have), you need to make sure you have messages like this, which indicate > that it really worked: > > WARNING: No sibling found for CPU 0. > WARNING: No sibling found for CPU 1. > > (and so on, if you have more than 2 CPU's) But what about machines that don't enumerate physical processors before logical? The comment in setup.c implies that the order that the BIOS presents CPUs is undefined and if you're unlucky enough to have a machine that presents the CPUs as physical, logical, physical, logical, etc you're screwed. Jim. - 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/