From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750935Ab2KXFG2 (ORCPT ); Sat, 24 Nov 2012 00:06:28 -0500 Received: from terminus.zytor.com ([198.137.202.10]:35733 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750706Ab2KXFG0 (ORCPT ); Sat, 24 Nov 2012 00:06:26 -0500 Message-ID: <50B055C8.2030209@zytor.com> Date: Fri, 23 Nov 2012 21:06:16 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121029 Thunderbird/16.0.2 MIME-Version: 1.0 To: Yuhong Bao CC: "mingo@kernel.org" , "linux-tip-commits@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "tglx@linutronix.de" Subject: Re: [tip:x86/smap] x86-32: Start out eflags and cr4 clean References: <1348529239-17943-1-git-send-email-hpa@linux.intel.com>, In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/23/2012 07:49 PM, Yuhong Bao wrote: >> + * Specifically, cr4 exists if and only if CPUID exists, >> + * which in turn exists if and only if EFLAGS.ID exists. > This may be true for *Intel* 486 CPUs as VME was implemented at the same time as CPUID, but I am not sure that it is true for AMD 486 CPUs. > > Yuhong Bao That is the architecture; if you know of a counterexample speak up. "I am not sure" doesn't count. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.