From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: memory barrier question Date: Tue, 21 Sep 2010 07:59:10 -0700 Message-ID: <20100921145910.GA3358@linux.vnet.ibm.com> References: <1284864421.30449.113.camel@pasglop> <20100919152638.GF3060@linux.vnet.ibm.com> <20100919215909.GG3060@linux.vnet.ibm.com> <1284944316.2957.795.camel@mulgrave.site> <20100920012915.GI3060@linux.vnet.ibm.com> <20100920182504.GD2408@linux.vnet.ibm.com> <4C97C366.80206@orcon.net.nz> <20100920204055.GJ2408@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from e3.ny.us.ibm.com ([32.97.182.143]:52493 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755906Ab0IUO7P (ORCPT ); Tue, 21 Sep 2010 10:59:15 -0400 Content-Disposition: inline In-Reply-To: <20100920204055.GJ2408@linux.vnet.ibm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Michael Cree Cc: Miklos Szeredi , James.Bottomley@HansenPartnership.com, benh@kernel.crashing.org, dhowells@redhat.com, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org On Mon, Sep 20, 2010 at 01:40:55PM -0700, Paul E. McKenney wrote: > On Tue, Sep 21, 2010 at 08:26:14AM +1200, Michael Cree wrote: > > On 21/09/10 06:25, Paul E. McKenney wrote: > > >But do we really care about Alpha anymore? (I can see it now... The > > >Alpha portion of the kernel tree moves to staging...) > > > > I do. > > > > Sent from my Compaq Alpha XP1000 :-) > > In that case, an smp_read_barrier_depends() or rcu_dereference() is > also required... Wait a minute... I finally got a chance to look up the system. This system has only a single Alpha CPU, right? If so, just build a UP kernel and be happy. No need to worry about any of these SMP issues. So, an alternative proposal -- support only UP kernels on Alpha. ;-) Thanx, Paul