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: [email protected] [mailto:[email protected]] On Behalf Of Arjan van de Ven
Sent: 2006年11月2日 17:16
To: Jun Sun
Cc: [email protected]
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!
--
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