From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner+w=401wt.eu-S1756697AbYFTUgB@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1756697AbYFTUgB (ORCPT <rfc822;w@1wt.eu>);
	Fri, 20 Jun 2008 16:36:01 -0400
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762160AbYFTUW1
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Fri, 20 Jun 2008 16:22:27 -0400
Received: from gw.goop.org ([64.81.55.164]:46516 "EHLO mail.goop.org"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1762155AbYFTUWZ (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Fri, 20 Jun 2008 16:22:25 -0400
Message-ID: <485C117E.8070706@goop.org>
Date: Fri, 20 Jun 2008 13:22:22 -0700
From: Jeremy Fitzhardinge <jeremy@goop.org>
User-Agent: Thunderbird 2.0.0.14 (X11/20080501)
MIME-Version: 1.0
To: Linus Torvalds <torvalds@linux-foundation.org>
CC: xen-devel <xen-devel@lists.xensource.com>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       kvm-devel <kvm-devel@lists.sourceforge.net>, benh@kernel.crashing.org,
       x86@kernel.org, LKML <linux-kernel@vger.kernel.org>,
       Virtualization Mailing List <virtualization@lists.osdl.org>,
       Hugh Dickins <hugh@veritas.com>, Ingo Molnar <mingo@elte.hu>,
       Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1 of 4] mm: add a ptep_modify_prot transaction abstraction
References: <alpine.LFD.1.10.0806181723400.2907@woody.linux-foundation.org>	<4859AA47.2020903@goop.org>	<alpine.LFD.1.10.0806181743390.2907@woody.linux-foundation.org>	<alpine.LFD.1.10.0806182050470.2907@woody.linux-foundation.org>	<20080619115832.GM15228@elte.hu>	<alpine.LFD.1.10.0806190928100.2907@woody.linux-foundation.org>	<20080619164708.GA32190@elte.hu>	<20080620101028.GA23664@elte.hu> <485BFFC4.3070902@goop.org>	<alpine.LFD.1.10.0806201211560.3167@woody.linux-foundation.org>	<20080620195620.GA20183@elte.hu>	<alpine.LFD.1.10.0806201302350.3167@woody.linux-foundation.org> <485C1000.8020806@goop.org>
In-Reply-To: <485C1000.8020806@goop.org>
X-Enigmail-Version: 0.95.6
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Jeremy Fitzhardinge wrote:
> Linus Torvalds wrote:
>   
>> On Fri, 20 Jun 2008, Ingo Molnar wrote:
>>   
>>     
>>> okay - Jeremy, could you try the fix below? (or tip/master, i just 
>>> pushed this out)
>>>     
>>>       
>> Actually, don't try that one.
>>
>> It needs to be a _byte_ registers, so "ir" was wrong. You need "iq".
>>   
>>     
>
> Doesn't work, unfortunately:
> {standard input}:20511: Error: Incorrect register `%eax' used with `b' 
> suffix
>
>         lock; orb %eax,1(%rdi)  # tmp64,
>   

This does work:

                asm volatile(LOCK_PREFIX "orb %1,%0"
                        : CONST_MASK_ADDR(nr, addr)
                        : "iq" ((u8)CONST_MASK(nr))
                        : "memory");

(ie, explicitly casting the mask to u8)

    J