From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 20 May 2001 21:48:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 20 May 2001 21:47:57 -0400 Received: from penguin.e-mind.com ([195.223.140.120]:31748 "EHLO penguin.e-mind.com") by vger.kernel.org with ESMTP id ; Sun, 20 May 2001 21:47:44 -0400 Date: Mon, 21 May 2001 03:47:26 +0200 From: Andrea Arcangeli To: "David S. Miller" Cc: Andrew Morton , Ivan Kokshaysky , Richard Henderson , linux-kernel@vger.kernel.org Subject: Re: alpha iommu fixes Message-ID: <20010521034726.G30738@athlon.random> In-Reply-To: <20010518214617.A701@jurassic.park.msu.ru> <20010519155502.A16482@athlon.random> <20010519231131.A2840@jurassic.park.msu.ru> <20010520044013.A18119@athlon.random> <3B07AF49.5A85205F@uow.edu.au> <20010520154958.E18119@athlon.random> <3B07CF20.2ABB5468@uow.edu.au> <20010520163323.G18119@athlon.random> <15112.26868.5999.368209@pizda.ninka.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <15112.26868.5999.368209@pizda.ninka.net>; from davem@redhat.com on Sun, May 20, 2001 at 06:01:40PM -0700 X-GnuPG-Key-URL: http://e-mind.com/~andrea/aa.gnupg.asc X-PGP-Key-URL: http://e-mind.com/~andrea/aa.asc Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, May 20, 2001 at 06:01:40PM -0700, David S. Miller wrote: > > Andrea Arcangeli writes: > > > Well this is news to me. No drivers understand this. > > > > Yes, almost all drivers are buggy. > > No, the interface says that the DMA routines may not return failure. The alpha returns a faliure since day zero of iommu support, the sparc64 has too otherwise it's even more buggy than alpha when the machine runs out of pci virtual address space. > If you want to change the DMA api to act some other way, then fine > please propose it, but do not act as if today they have to act this > way because that is simply not true. About the pci_map_single API I'd like if bus address 0 would not be the indication of faluire, mainly on platforms without an iommu that's not nice, x86 happens to get it right only because the physical page zero is reserved for completly other reasons. so we either add a err parameter to the pci_map_single, or we define a per-arch bus address to indicate an error, either ways are ok from my part. Andrea