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

Andi Kleen
2007-04-24T21:13:07Z

On Tuesday 24 April 2007 22:33:04 Ashok Raj wrote:

> With PCIE there is some benefit to keep dma addr low for performance reasons,
> since it will use 32bit Transaction level packets instead of 64bit.
>
> This reservation is only required if we have some legacy device under a p2p
> where its required to share its addr space with other devices. We could
> implement a default when one is not specified to keep things simple.

We already have a couple of other IOMMU architectures who essentially have the same
problem. Have you checked how they solve this?

-Andi