From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933429Ab1JNVw7 (ORCPT ); Fri, 14 Oct 2011 17:52:59 -0400 Received: from terminus.zytor.com ([198.137.202.10]:49328 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751930Ab1JNVw6 (ORCPT ); Fri, 14 Oct 2011 17:52:58 -0400 Message-ID: <4E98AF09.6040306@zytor.com> Date: Fri, 14 Oct 2011 14:52:09 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0) Gecko/20110927 Thunderbird/7.0 MIME-Version: 1.0 To: Jeremy Fitzhardinge CC: Steven Rostedt , "David S. Miller" , David Daney , Michael Ellerman , Jan Glauber , Jason Baron , the arch/x86 maintainers , Xen Devel , Linux Kernel Mailing List , Ingo Molnar , Peter Zijlstra , Jeremy Fitzhardinge Subject: Re: [PATCH RFC V4 09/10] x86/jump_label: use GENERIC_NOP5_ATOMIC instead of jmp5 +0 References: <34ede5db1571d541a5c3fc49923bb353a37dd431.1318464413.git.jeremy.fitzhardinge@citrix.com> <4E97067A.2070305@zytor.com> <4E9716B8.8050406@goop.org> In-Reply-To: <4E9716B8.8050406@goop.org> 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 10/13/2011 09:50 AM, Jeremy Fitzhardinge wrote: > On 10/13/2011 08:40 AM, H. Peter Anvin wrote: >> On 10/12/2011 05:08 PM, Jeremy Fitzhardinge wrote: >>> From: Jeremy Fitzhardinge >>> >>> GENERIC_NOP5_ATOMIC should make a better nop. >>> >> On 32 bits, yes. On 64 bits you should use P6_NOP5_ATOMIC. > > So the cleanest way of fixing that is to make the GENERIC_NOP* be > defined to P6_NOP* on 64-bit then? Assuming I'm correct in guessing > that the intent of GENERIC_NOP* is "a basically good-enough NOP that > will work on any x86". > No, GENERIC_NOPs are not valid on 64 bits at all. -hpa