From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754002Ab0JDVyF (ORCPT ); Mon, 4 Oct 2010 17:54:05 -0400 Received: from terminus.zytor.com ([198.137.202.10]:43583 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751336Ab0JDVyE (ORCPT ); Mon, 4 Oct 2010 17:54:04 -0400 Message-ID: <4CAA4CCB.5090205@zytor.com> Date: Mon, 04 Oct 2010 14:53:15 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc13 Thunderbird/3.1.4 MIME-Version: 1.0 To: Borislav Petkov , Linus Torvalds , Ingo Molnar , Thomas Gleixner , lkml Subject: Re: [PATCH] x86, cpu: Fix X86_FEATURE_NOPL References: <4CA89681.8000202@zytor.com> <20101003152212.GA13233@liondog.tnic> <20101003201139.GA16532@liondog.tnic> <20101004073127.GA20305@liondog.tnic> <4CAA4102.3070205@zytor.com> <4CAA455D.8000902@zytor.com> <20101004214838.GA26084@liondog.tnic> In-Reply-To: <20101004214838.GA26084@liondog.tnic> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/04/2010 02:48 PM, Borislav Petkov wrote: > > I think the cleanup should be easy: on 64-bit unconditionally return > p6_nops in find_nop_table() since every 64-bit processor should support > them and on 32-bit never return p6_nops since X86_FEATURE_NOPL is not > set there and fall back to intel_nops on non-AMD. Which means we can get > rid of X86_FEATURE_NOPL altogether. Too radical? > FWIW, if P6_NOPs work as well as 66...90 on AMD, I'd much rather switch to the fixed sequence for all 64-bit processors. -hpa