Re: [linux-dvb] [PATCH] Userspace tuner

[Joerg Roedel <joro@8bytes.org>]

On Fri, Sep 14, 2007 at 11:57:59AM +0400, Manu Abraham wrote:
> >>> What do you think about IOMMU?
> >>>
> >>>
> >> Just because AMD or INTEL want to invent some whizzy new technology it
> >> doesn't say anything about the TV card development and retail business.
> >> Intel and AMD have teams of Linux engineers helping operating system
> >> developers bring their ideas and technologies to new platforms. That's a
> >> million miles away from any of the TV board vendors I know of, who have
> >> little or NO fulltime linux developers and consider the < 5% market
> >> fringe at best.
> >>
> > 
> > it helps to virtualize devices and introduces newer features for that.
> > Some interesting projects could be derrived out of that, there are
> > quite a few interesting papers floating around how drivers could be
> > handled in future.
> > 
> 
> IOMMU can be considered similar to the AGP GART, which is similar,
> remapping the Addresses, as far as i understand.

Common new IOMMUs have only very few in common with the AGP GART. In
fact, with current modern IOMMU hardware it will be possible to
implement secure userspace device drivers that are even able to do DMA.
This is not possible with the GART.

> Though you get a physical to virtual translation, what about interrupts,

Modern IOMMUs are able to remap interrupts. This will solve the problem
with PCI interrupt sharing.

Joerg