From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 21 May 2001 06:55:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 21 May 2001 06:55:33 -0400 Received: from pizda.ninka.net ([216.101.162.242]:7553 "EHLO pizda.ninka.net") by vger.kernel.org with ESMTP id ; Mon, 21 May 2001 06:55:19 -0400 From: "David S. Miller" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15112.62483.731973.549006@pizda.ninka.net> Date: Mon, 21 May 2001 03:55:15 -0700 (PDT) To: Andi Kleen Cc: Andrea Arcangeli , Andrew Morton , Ivan Kokshaysky , Richard Henderson , linux-kernel@vger.kernel.org Subject: Re: alpha iommu fixes In-Reply-To: <20010521124225.A3417@gruyere.muc.suse.de> In-Reply-To: <20010521034726.G30738@athlon.random> <15112.48708.639090.348990@pizda.ninka.net> <20010521105944.H30738@athlon.random> <15112.55709.565823.676709@pizda.ninka.net> <20010521112357.A1718@gruyere.muc.suse.de> <15112.57377.723591.710628@pizda.ninka.net> <20010521114216.A1968@gruyere.muc.suse.de> <15112.59192.613218.796909@pizda.ninka.net> <20010521122753.A2507@gruyere.muc.suse.de> <15112.61258.251051.960811@pizda.ninka.net> <20010521124225.A3417@gruyere.muc.suse.de> X-Mailer: VM 6.75 under 21.1 (patch 13) "Crater Lake" XEmacs Lucid Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen writes: > On Mon, May 21, 2001 at 03:34:50AM -0700, David S. Miller wrote: > > egrep illegal_highdma net/core/dev.c > > There is just no portable way for the driver to figure out if it should > set this flag or not. e.g. acenic.c gets it wrong: it is unconditionally > set even on IA32. Currently it requires an architecture ifdef to set properly. Well, certainly, this could perhaps be a bug in the Acenic driver. It should check if DAC cycles can be used on the platform, for example. But please, let's get back to the original problem though. The original claim is that the situation was not handled at all. All I'm trying to say is simply that the net stack does check via illegal_highdma() the condition you stated was not being checked at all. To me it sounded like you were claiming that HIGHMEM pages went totally unchecked through device transmit, and that is totally untrue. If you were trying to point out the problem with what the Acenic driver is doind, just state that next time ok? :-) There is no question that what Acenic is doing with ifdefs needs a clean portable solution. This will be part of the 64-bit DAC API interfaces (whenever those become really necessary, I simply don't see the need right now). Plainly, I'm going to be highly reluctant to make changes to the PCI dma API in 2.4.x It is already hard enough to get all the PCI drivers in line and using it. Suggesting this kind of change is similar to saying "let's change the arguments to request_irq()". We would do it to fix a true "people actually hit this" kind of bug, of course. Yet we would avoid it at all possible costs due to the disruption this would cause. I'm not trying to be a big bad guy about this. What I'm trying to do is make sure at least one person (me :-) is thinking about the ramifications any such change has on all current drivers which use these interfaces already. And also, to port maintainers... Later, David S. Miller davem@redhat.com