Messages in this thread | | | Subject | RE: Can Linux live without DMA zone? | Date | Thu, 2 Nov 2006 18:33:07 +0800 | From | "Conke Hu" <> |
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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年11月2日 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
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