Re: [PATCH 3/9] add frontend implementation for the IOMMU API

From: Muli Ben-Yehuda
Date: Mon Dec 01 2008 - 08:02:26 EST

On Mon, Dec 01, 2008 at 01:00:26PM +0100, Joerg Roedel wrote:

> > > > The majority of the names (include/linux/iommu.h, iommu.c,
> > > > iommu_ops, etc) looks too generic? We already have lots of
> > > > similar things (e.g. arch/{x86,ia64}/asm/iommu.h, several
> > > > archs' iommu.c, etc). Such names are expected to be used by
> > > > all the IOMMUs.
> > >
> > > The API is already useful for more than KVM. I also plan to
> > > extend it to support more types of IOMMUs than VT-d and AMD
> > > IOMMU in the future. But these changes are more intrusive than
> > > this patchset and need more discussion. I prefer to do small
> > > steps into this direction.
> >
> > Can you be more specific? What IOMMU could use this? For example,
> > how GART can use this? I think that people expect the name 'struct
> > iommu_ops' to be an abstract for all the IOMMUs (or the majority
> > at least). If this works like that, the name is a good choice, I
> > think.
> GART can't use exactly this. But with some extensions we can make it
> useful for GART and GART-like IOMMUs too. For example we can emulate
> domains in GART by partitioning the GART aperture space.

That would only work with a pvdma API, since GART doesn't support
multiple address spaces, and you don't get the isolation properties of
a real IOMMU, so... why would you want to do that?

The First Workshop on I/O Virtualization (WIOV '08)
Dec 2008, San Diego, CA,
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