Re: [Intel IOMMU][patch 8/8] Preserve some Virtual Address when devicescannot address entire range.

[H. Peter Anvin]

Andi Kleen wrote:
> On Tuesday 24 April 2007 23:50:26 David Miller 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 :-)
>
> There's also a 2GB only megaraid RAID controller that's pretty popular 
> because Dell shipped it for a long time.

You can probably find almost any possible bitmask if you look long 
enough.  Hardware vendors are notorious for this kind of "optimizations".

	-hpa
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