From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030299AbWD1Hju (ORCPT ); Fri, 28 Apr 2006 03:39:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030302AbWD1Hju (ORCPT ); Fri, 28 Apr 2006 03:39:50 -0400 Received: from smtp106.mail.mud.yahoo.com ([209.191.85.216]:19121 "HELO smtp106.mail.mud.yahoo.com") by vger.kernel.org with SMTP id S1030299AbWD1Hjs (ORCPT ); Fri, 28 Apr 2006 03:39:48 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=gqUCKnJyy+WDm81I4dQTqXQozXxQcw/lcNZImHEzwZyb74ixtLYkthw+BfASlVWs1ddJg9ESmnAZq1gS9gsuadcrQbrNXPd8tffUPzzuI/ByiuPgZpBi+1cGIgM2b/sK2V0HpHu0mIrGwziMpxDoU19Q2FjV0CLV8LsynNbu6q8= ; Message-ID: <4451C23D.5000002@yahoo.com.au> Date: Fri, 28 Apr 2006 17:20:29 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Andi Kleen CC: Chris Wright , Linux Kernel Mailing List , zach@vmware.com, torvalds@osdl.org Subject: Re: [PATCH] x86/PAE: Fix pte_clear for the >4GB RAM case References: <200604272001.k3RK1dmX007637@hera.kernel.org> <200604280808.44496.ak@suse.de> <20060428062704.GH2909@sorel.sous-sol.org> <200604280829.29164.ak@suse.de> In-Reply-To: <200604280829.29164.ak@suse.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen wrote: > No it was me who was confused sorry. Somehow i thought it was defined > away for !SMP > > (which would make sense because why would you want a compile barrier > for a barrier that is only needed on SMP?) It is maybe not clearly named. smp_wmb() is a memory barrier to the regular (eg. RAM) cache coherency domain AFAICT. wmb() is also a barrier to io memory. There is nothing to distinguish SMP and UP. I guess sometimes smp_ barriers would not even have to be a barrier() on UP, but other times they would have to be (eg. in the case of concurrent interrupts, context switches). -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com