Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755285AbYKKFyS (ORCPT ); Tue, 11 Nov 2008 00:54:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751260AbYKKFyD (ORCPT ); Tue, 11 Nov 2008 00:54:03 -0500 Received: from sh.osrg.net ([192.16.179.4]:39611 "EHLO sh.osrg.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751186AbYKKFyB (ORCPT ); Tue, 11 Nov 2008 00:54:01 -0500 Date: Tue, 11 Nov 2008 14:53:46 +0900 To: cl@linux-foundation.org Cc: y-goto@jp.fujitsu.com, tony.luck@intel.com, fujita.tomonori@lab.ntt.co.jp, 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? From: FUJITA Tomonori In-Reply-To: References: <20081110121123.F82A.E1E9C6FF@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <20081111145418P.fujita.tomonori@lab.ntt.co.jp> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 911 Lines: 17 On Mon, 10 Nov 2008 16:06:52 -0600 (CST) Christoph Lameter wrote: > On Mon, 10 Nov 2008, Yasunori Goto wrote: > > > Even if a device allows over 4G access and the driver doesn't specify > > GFP_DMA, dma_alloc_coherent() returns under 4G area. > > GFP_DMA can become 0 for configurations that have > !CONFIG_ZONE_DMA. Then all of memory is available. > > The call is subarch specific. So f.e. Altix sn_dma_alloc_coherent does > not set __GFP_DMA. 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). -- 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/