Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752612AbYKKUdR (ORCPT ); Tue, 11 Nov 2008 15:33:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751692AbYKKUdE (ORCPT ); Tue, 11 Nov 2008 15:33:04 -0500 Received: from nlpi053.sbcis.sbc.com ([207.115.36.82]:48532 "EHLO nlpi053.prodigy.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751667AbYKKUdE (ORCPT ); Tue, 11 Nov 2008 15:33:04 -0500 Date: Tue, 11 Nov 2008 14:32:46 -0600 (CST) From: Christoph Lameter X-X-Sender: cl@quilx.com To: FUJITA Tomonori cc: y-goto@jp.fujitsu.com, tony.luck@intel.com, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, joerg.roedel@amd.com Subject: Re: [Q] Why does dma_alloc_coherent() of ia64 GFP_DMA? In-Reply-To: <20081111145418P.fujita.tomonori@lab.ntt.co.jp> Message-ID: References: <20081110121123.F82A.E1E9C6FF@jp.fujitsu.com> <20081111145418P.fujita.tomonori@lab.ntt.co.jp> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Spam-Score: -2.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 681 Lines: 16 On Tue, 11 Nov 2008, FUJITA Tomonori wrote: > Is it because it does some kinda address translation > (provider->dma_map_consistent) later? The zone flag is meaningless if > you do sorta address translation (e.g. hardware IOMMU like VT-d). Yes it can do address translation. Therefore a < 4G address can show up at any 64 bit address. So no need for a special DMA zone. The same is true for more x86_64 platforms that have an IOMMU. -- 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/