Re: [PATCH] uio_pci_generic does not export memory resources

Alex Williamson
2012-06-08T15:07:04Z

On Fri, 2012-06-08 at 16:47 +0200, Dominic Eschweiler wrote:
> Am Freitag, den 08.06.2012, 08:16 -0600 schrieb Alex Williamson:
> > Yes, thanks Jan. This is exactly what VFIO does. VFIO provides
> > secure config space access, resource access, DMA mapping services, and
> > full interrupt support to userspace.
>
> I know about VFIO, but we need some support for that stuff relatively
> soon. That's the reason why I'm currently working on it to make UIO DMA
> capable. My extensions probably do not play well with IOMMUs and they
> therefore won't make it to mainline anyhow (i learned that today ;-).

Yeah, VFIO was originally started by Tom Lyon as a uio extension to
support DMA mapping and more extensive interrupt handling, but it became
an entire re-write of uio. Now we've had to extend in to iommu grouping
to get the DMA protection that we're really after.

> > I'm currently working to get this upstream, probably targeting 3.6 at
> > this point, and would love to have more users to help make that
> > happen.
>
> Yes, you are faster than I'm able to ask. 3.6 is a good target and
> really would like to support that.
>
> > Please take a look at the vfio-3.4 branch in the tree above. See this
> > tree for Qemu's usage of VFIO for device assignment ...
>
> OK, I take look at it and report back (off the list). Please write me an
> email if you need support.

Thanks,
Alex