Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753580AbZF3Mt0 (ORCPT ); Tue, 30 Jun 2009 08:49:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752330AbZF3MtS (ORCPT ); Tue, 30 Jun 2009 08:49:18 -0400 Received: from moutng.kundenserver.de ([212.227.17.9]:55305 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752710AbZF3MtS (ORCPT ); Tue, 30 Jun 2009 08:49:18 -0400 From: Arnd Bergmann To: Alan Cox Subject: Re: [PATCH][RFC] asm-generic:remove calling flush_write_buffers() in dma_sync_*_for_cpu Date: Tue, 30 Jun 2009 14:48:54 +0200 User-Agent: KMail/1.11.90 (Linux/2.6.30-9-generic; KDE/4.2.90; x86_64; ; ) Cc: Joerg Roedel , tom.leiming@gmail.com, fujita.tomonori@lab.ntt.co.jp, linux-kernel@vger.kernel.org, akpm@linux-foundation.org References: <1246199959-6548-1-git-send-email-tom.leiming@gmail.com> <200906301434.26815.arnd@arndb.de> <20090630134000.23674147@lxorguk.ukuu.org.uk> In-Reply-To: <20090630134000.23674147@lxorguk.ukuu.org.uk> X-Face: I@=L^?./?$U,EK.)V[4*>`zSqm0>65YtkOe>TFD'!aw?7OVv#~5xd\s,[~w]-J!)|%=]> =?utf-8?q?+=0A=09=7EohchhkRGW=3F=7C6=5FqTmkd=5Ft=3FLZC=23Q-=60=2E=60Y=2Ea=5E?= =?utf-8?q?3zb?=) =?utf-8?q?+U-JVN=5DWT=25cw=23=5BYo0=267C=26bL12wWGlZi=0A=09=7EJ=3B=5Cwg?= =?utf-8?q?=3B3zRnz?=,J"CT_)=\H'1/{?SR7GDu?WIopm.HaBG=QYj"NZD_[zrM\Gip^U MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200906301448.55064.arnd@arndb.de> X-Provags-ID: V01U2FsdGVkX19U8ngWxdWSrc1oPjcMaHk9Vm827Fp3l2QfqPN t6LMlZQoqi6J+u3WaAv1MaKLZgdwxTTYeHq0nljAOC7GEx+U9u d+vpCzrk8G++ipeT8vyiw== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1173 Lines: 24 On Tuesday 30 June 2009, Alan Cox wrote: > > Ok. The Winchip also does not have an IOMMU or the need for SWIOTLB, so > > I guess it would be ok to move the flush_write_buffers() out of the common > > code into the x86 pci-nommu implementation. That one is also the only > > place that calls flush_write_buffers() in dma_map_(). > > What about non x86 - this is asm-generic you are playing with and its the > kind of change that causes evil really hard to track down and subtle > corruptions and user data loss if you get it wrong. Non-x86 is the real motivation for the patch, because the flush_write_buffers call in this file is currently not implemented and causes build errors on everything but x86, frv, ia64 and m32r, where the latter two implement it as an empty macro. The only users of the file right now are x86 and ia64, and ia64 only added the empty flush_write_buffers() definition in order to use it. Arnd <>< -- 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/