From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 21 Sep 2001 14:45:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 21 Sep 2001 14:45:28 -0400 Received: from hermes.toad.net ([162.33.130.251]:42722 "EHLO hermes.toad.net") by vger.kernel.org with ESMTP id ; Fri, 21 Sep 2001 14:45:17 -0400 Message-ID: <3BAB8AB2.C6DB27B0@yahoo.co.uk> Date: Fri, 21 Sep 2001 14:45:06 -0400 From: Thomas Hood X-Mailer: Mozilla 4.77 [en] (X11; U; Linux 2.4.9-ac10 i686) X-Accept-Language: en MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: Re: [PATCH] parport_pc.c PnP BIOS sanity check In-Reply-To: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Thanks for the replies. I'd like to underline Alan Cox's reply that DMA0 _is_ usable. In fact, my sound chip is configured to use DMA0. If (and only if) parport _cannot_ use DMA0 for some reason then the sanity check is justified. In that case I'd just ask that a short comment be added to the code that gives the reason. Cheers Thomas Ignacio Vazquez-Abrams wrote: > DMA0 is reserved for memory refresh. It _can't_ be used for anything else, > therefore a value of 0 is representative of no value whatsoever. Alan Cox wrote: > This has been unsafe since about 1995, when DMA 0 became available as PC's > stopped using the ISA DMA engine for memory refresh (a very neat original PC > hack) Gunther Mayer wrote: > 1) > I think I saw some BIOS report DMA0 for "none" (could even have > been ACPI which is returning PNP formatted legacy resource data). > 2) > I have never seen DMA0 for parport configured by a BIOS. > 3) > Try "lssuperio" if you want the real hardware thing. > > This qualifies the code as it is as a sanity check.