Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751310AbWCIEsI (ORCPT ); Wed, 8 Mar 2006 23:48:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751128AbWCIEsI (ORCPT ); Wed, 8 Mar 2006 23:48:08 -0500 Received: from ozlabs.org ([203.10.76.45]:50103 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S1750796AbWCIEsF (ORCPT ); Wed, 8 Mar 2006 23:48:05 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17423.45681.476222.143773@cargo.ozlabs.ibm.com> Date: Thu, 9 Mar 2006 15:43:29 +1100 From: Paul Mackerras To: Jesse Barnes Cc: Linus Torvalds , akpm@osdl.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, Alan Cox , linuxppc64-dev@ozlabs.org Subject: Re: [PATCH] Document Linux's memory barriers [try #2] In-Reply-To: <200603082034.00238.jbarnes@virtuousgeek.org> References: <17423.32792.500628.226831@cargo.ozlabs.ibm.com> <200603082034.00238.jbarnes@virtuousgeek.org> X-Mailer: VM 7.19 under Emacs 21.4.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 836 Lines: 21 Jesse Barnes writes: > So ultimately mmiowb() is the only thing drivers really have to care > about on Altix (assuming they do DMA mapping correctly), and the rules > for that are fairly simple. Then they can additionally use > read_relaxed() to optimize performance a bit (quite a bit on big > systems). If I can be sure that all the drivers we care about on PPC use mmiowb correctly, I can reduce or eliminate the barrier in write*, which would be nice. Which drivers have been audited to make sure they use mmiowb correctly? In particular, has the USB driver been audited? Paul. - 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/