Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752809AbWKBKdd (ORCPT ); Thu, 2 Nov 2006 05:33:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752810AbWKBKdd (ORCPT ); Thu, 2 Nov 2006 05:33:33 -0500 Received: from outbound-sin.frontbridge.com ([207.46.51.80]:35203 "EHLO outbound2-sin-R.bigfish.com") by vger.kernel.org with ESMTP id S1752809AbWKBKdc convert rfc822-to-8bit (ORCPT ); Thu, 2 Nov 2006 05:33:32 -0500 X-BigFish: V Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="gb2312" Content-Transfer-Encoding: 8BIT Subject: RE: Can Linux live without DMA zone? X-MimeOLE: Produced By Microsoft Exchange V6.5 Date: Thu, 2 Nov 2006 18:33:07 +0800 Message-ID: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: Can Linux live without DMA zone? Thread-Index: Acb+X8QzRhWkOtZqSru5oAg7bjU8aQACkDeA From: "Conke Hu" To: "Arjan van de Ven" , "Jun Sun" Cc: X-OriginalArrivalTime: 02 Nov 2006 10:33:11.0812 (UTC) FILETIME=[4BC97440:01C6FE6A] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2105 Lines: 55 Most PCs do not have ISA or floppy, so maybe we could add an option to enable DMA zone or not. Best regards, Conke @ AMD, Inc. -----Original Message----- From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Arjan van de Ven Sent: 2006??11??2?? 17:16 To: Jun Sun Cc: linux-kernel@vger.kernel.org Subject: Re: Can Linux live without DMA zone? On Wed, 2006-11-01 at 18:15 -0800, Jun Sun wrote: > I am trying to reserve a block of memory (>16MB) starting from 0 and hide it > from kernel. A consequence is that DMA zone now has size 0. That causes > many drivers to grief (OOMs). > > I see two ways out: > > 1. Modify individual drivers and convince them not to alloc with GFP_DMA. > I have been trying to do this but do not seem to see an end of it. :) > > 2. Simply lie and increase MAX_DMA_ADDRESS to really big (like 1GB) so that > the whole memory region belongs to DMA zone. > > #2 sounds pretty hackish. I am sure something bad will happen > sooner or later (like what?). But so far it appears to be working fine. > > The fundamental question is: Has anybody tried to run Linux without 0 sized > DMA zone before? Am I doing something that nobody has done before (which is > something really hard to believe these days with Linux :P)? on a PC there are still devices that need memory in the lower 16Mb..... (like floppy) Maybe you should reserve another area of memory instead! -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org - 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/ - 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/