Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756736Ab0DWVgG (ORCPT ); Fri, 23 Apr 2010 17:36:06 -0400 Received: from claw.goop.org ([74.207.240.146]:54401 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753307Ab0DWVgA (ORCPT ); Fri, 23 Apr 2010 17:36:00 -0400 Message-ID: <4BD212BF.60707@goop.org> Date: Fri, 23 Apr 2010 14:35:59 -0700 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc12 Lightning/1.0b2pre Thunderbird/3.0.4 MIME-Version: 1.0 To: Zachary Amsden CC: Avi Kivity , Glauber Costa , Peter Zijlstra , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Marcelo Tosatti Subject: Re: [PATCH 1/5] Add a global synchronization point for pvclock References: <1271675100.1674.818.camel@laptop> <4BCC3A3E.9070909@redhat.com> <20100419142158.GD14158@mothafucka.localdomain> <4BCC69D5.3050209@redhat.com> <1271688411.1488.248.camel@laptop> <4BCC8246.9040202@goop.org> <4BCD748E.7080007@redhat.com> <4BCDF12C.1020702@goop.org> <4BCDF85C.3000004@redhat.com> <4BCE0399.2010708@goop.org> <20100422131113.GA3364@mothafucka.localdomain> <4BD0FB92.4060301@redhat.com> <4BD169B5.4000409@redhat.com> <4BD211B9.5080707@redhat.com> In-Reply-To: <4BD211B9.5080707@redhat.com> X-Enigmail-Version: 1.0.1 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 Content-Length: 757 Lines: 19 On 04/23/2010 02:31 PM, Zachary Amsden wrote: > Does lfence / mfence actually serialize? I thought there was some > great confusion about that not being the case on all AMD processors, > and possibly not at all on Intel. > > A trap, however is a great way to serialize. > > I think, there is no serializing instruction which can be used from > userspace which does not trap, at least, I don't know one off the top > of my head. rsm is not technically privileged... but not quite usable from usermode ;) J -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/