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

From: Andi Kleen
Date: Tue Apr 24 2007 - 15:33:45 EST

On Tuesday 24 April 2007 08:03:07 Ashok Raj wrote:
> Some devices may not support entire 64bit DMA. In a situation where such
> devices are co-located in a shared domain, we need to ensure there is some
> address space reserved for such devices without the low addresses getting
> depleted by other devices capable of handling high dma addresses.

Sorry, but you need to find some way to make this usually work without special
options. Otherwise users will be unhappy.

An possible way would be to allocate space upside down from the limit of the
device. Then the lower areas should be usually free.

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