From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753056Ab0JDVvx (ORCPT ); Mon, 4 Oct 2010 17:51:53 -0400 Received: from terminus.zytor.com ([198.137.202.10]:57724 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752776Ab0JDVvw (ORCPT ); Mon, 4 Oct 2010 17:51:52 -0400 Message-ID: <4CAA4C2B.2050909@zytor.com> Date: Mon, 04 Oct 2010 14:50:35 -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 >> >> Agreed that this should be cleaned up. However, in the meantime I'd >> like to keep Borislav's patch in the tree since it makes the code >> technically correct at least. > > 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? > This is fine with me, but you may want to check with your employer if the Intel NOPs will perform slower than the 66 ... 90 NOPs on AMD processors. -hpa