From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e34.co.us.ibm.com (e34.co.us.ibm.com [32.97.110.152]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e34.co.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTP id 83A72DDE42 for ; Sat, 5 May 2007 08:13:14 +1000 (EST) Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e34.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id l44MDALL006624 for ; Fri, 4 May 2007 18:13:10 -0400 Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v8.3) with ESMTP id l44MD9Cj179748 for ; Fri, 4 May 2007 16:13:09 -0600 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l44MD9VF013339 for ; Fri, 4 May 2007 16:13:09 -0600 Date: Fri, 4 May 2007 17:13:09 -0500 To: Scott Wood Subject: Re: [PATCH v2] gianfar: Add I/O barriers when touching buffer descriptor ownership. Message-ID: <20070504221309.GR6193@austin.ibm.com> References: <20070502195712.GA16541@ld0162-tx32.am.freescale.net> <4638F0C4.2000406@freescale.com> <4638F734.2040809@freescale.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <4638F734.2040809@freescale.com> From: linas@austin.ibm.com (Linas Vepstas) Cc: netdev@vger.kernel.org, jgarzik@pobox.com, linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, May 02, 2007 at 03:40:20PM -0500, Scott Wood wrote: > > Well, Segher doesn't want me to use iobarrier (because it's not I/O). > Andy doesn't want me to use wmb() (because it's sync). I don't think > something like gfar_wmb() would be appropriate. So the remaining > options are either eieio(), ? Just curious... the original intent of eieio was to order I/O, such as MMIO; it has no effect on memory that isn't marked cache-inhibited or write-trhough or guarded. Has this changed? I guess I haven't kept up with the times ... is eieio now being used to provide some other kind of barrier? Is eieio providing some sort of SMP synchronization side-effect? Point being: if Segher doesn't let you "use iobarrier (because it's not I/O)", then I don't understand why eieio would work (since that's for io only). --linas