From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753621AbYIVUah (ORCPT ); Mon, 22 Sep 2008 16:30:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751753AbYIVUa3 (ORCPT ); Mon, 22 Sep 2008 16:30:29 -0400 Received: from one.firstfloor.org ([213.235.205.2]:58024 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751024AbYIVUa3 (ORCPT ); Mon, 22 Sep 2008 16:30:29 -0400 Date: Mon, 22 Sep 2008 22:35:18 +0200 From: Andi Kleen To: FUJITA Tomonori Cc: andi@firstfloor.org, mingo@elte.hu, joerg.roedel@amd.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/3] fix GART to respect device's dma_mask about virtual mappings Message-ID: <20080922203518.GZ25711@one.firstfloor.org> References: <20080918182029.GO25711@one.firstfloor.org> <20080919071534C.fujita.tomonori@lab.ntt.co.jp> <20080919004431.GS25711@one.firstfloor.org> <20080923041203Q.fujita.tomonori@lab.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080923041203Q.fujita.tomonori@lab.ntt.co.jp> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 23, 2008 at 04:12:33AM +0900, FUJITA Tomonori wrote: > Sure, pci-nommu's map_sg/map_single doesn't handle it. But we handle > this issue somewhere else (like b44 keeps own DMA buffer)? Yes, b44 handles it on its own. It has to for 32bit which always has a nop map_sg/single. Also some other subsystems like the block layer do it implicitely. > 1. not all map_sg/map_single (e.g. pci-nommu) can't handle it. and especially i386 > 2. we already have workarounds for it somewhere else so > map_sg/map_single don't need to handle it. > 3. I changed GART map_sg/map_signle to handle it. I thought if it > can handle it, for example, b44 doesn't go the workaround path. It > would be a good thing. > 4. But GART cannot remap to addresses < 4GB reliably, so my above > argument doesn't always work. > 5. Then my patch doesn't break anything but it's almost meaningless. Correct. -Andi -- ak@linux.intel.com