Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760230AbXIZT3Z (ORCPT ); Wed, 26 Sep 2007 15:29:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755610AbXIZT3R (ORCPT ); Wed, 26 Sep 2007 15:29:17 -0400 Received: from sj-iport-2-in.cisco.com ([171.71.176.71]:61244 "EHLO sj-iport-2.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754784AbXIZT3P (ORCPT ); Wed, 26 Sep 2007 15:29:15 -0400 X-IronPort-AV: E=Sophos;i="4.21,198,1188802800"; d="scan'208";a="402059027" To: Grant Grundler Cc: akepner@sgi.com, Jesse Barnes , Jes Sorensen , Randy Dunlap , David Miller , linux-kernel@vger.kernel.org, James Bottomley Subject: Re: [PATCH 0/4] allow drivers to flush in-flight DMA X-Message-Flag: Warning: May contain useful information References: <20070925235843.GK30013@sgi.com> <20070926064950.GB30430@colo.lackof.org> From: Roland Dreier Date: Wed, 26 Sep 2007 12:29:12 -0700 In-Reply-To: <20070926064950.GB30430@colo.lackof.org> (Grant Grundler's message of "Wed, 26 Sep 2007 00:49:50 -0600") Message-ID: User-Agent: Gnus/5.1008 (Gnus v5.10.8) XEmacs/21.4.20 (linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-OriginalArrivalTime: 26 Sep 2007 19:29:12.0977 (UTC) FILETIME=[84D3C810:01C80073] Authentication-Results: sj-dkim-3; header.From=rdreier@cisco.com; dkim=pass ( sig from cisco.com/sjdkim3002 verified; ); Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1154 Lines: 26 > Can we define this API to provide the same semantics as the memory > that dma_alloc_coherent() returns? No, definitely not. The property of the mapping here is all about ordering with respect to other DMAs (from the same device) and nothing to do with coherency between the CPU's and device's view of the memory. > Sorry - this feels like a "color of the shed" argument, but isn't > this about DMA ordering attribute? > "dmaflush" is an action and not an attribute to me. I guess I don't love the "dmaflush" name, but the property of these mappings is exactly that DMA into one of these mappings also performs the action of flushing other in-flight DMAs. However I guess your point is a good one: the effect really desired is that DMAs to these mappings become visible strictly after earlier DMAs, and we don't care exactly how the effect is obtained. No good idea of a better name though. - R. - 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/