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Message-ID: <47B9B720.9020000@gmail.com>
Date: Mon, 18 Feb 2008 17:49:36 +0100
From: Jiri Slaby <jirislaby@...il.com>
To: Ke <kecore@...il.com>
CC: linux-kernel@...r.kernel.org
Subject: Re: PCI DMA address
On 02/18/2008 04:05 PM, Ke wrote:
> Hello all,
> How can kernel get the PCI DMA address above 16MB or 64MB?
Documentation/DMA*
> I hope that the all PCI devices can use a dma address above
> 0x1000000 at a higher memory.
Depends on how much is the device broken or what it can do.
IIRC you'll always get memory from DMA-zone for < ~0U dma_masks on kernels older
than 2.6.(around 10). If you set dma_masks to < ~0U, you will probably (in the
meaning, kernel will try to allocate from higher space and fall back to the
dma-zone) get higher pages nowadays. However I don't know how far this applies
also to systems with iommu in retrospective.
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