Re: [Intel IOMMU][patch 8/8] Preserve some Virtual Address whendevices cannot address entire range.

From: Alan Cox
Date: Tue Apr 24 2007 - 19:19:33 EST


On Tue, 24 Apr 2007 14:50:26 -0700 (PDT)
David Miller <davem@xxxxxxxxxxxxx> wrote:

> From: Ashok Raj <ashok.raj@xxxxxxxxx>
> Date: Tue, 24 Apr 2007 14:38:35 -0700
>
> > Its not clear if we have a very generic device breakage.. most devices
> > on these platforms are going to be more recent, (except maybe some
> > legacy fd)...
>
> I'm not so sure, there are some "modern" sound cards that have
> a 31-bit DMA addressing limitation because they use the 31st
> bit as a status bit in their DMA descriptors :-)

The sound stuff is going away bit by bit thankfully, but the 30bit DMA
limit is present on some more demented wireless chips still.

Alan
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