Re: [PATCH] VFIO driver: Non-privileged user level PCI drivers

[Michael S. Tsirkin]

On Wed, Jun 02, 2010 at 12:19:40PM +0200, Joerg Roedel wrote:
> On Wed, Jun 02, 2010 at 12:53:12PM +0300, Michael S. Tsirkin wrote:
> > On Wed, Jun 02, 2010 at 11:42:01AM +0200, Joerg Roedel wrote:
> 
> > > IMO a seperate iommu-userspace driver is a nightmare for a userspace
> > > interface. It is just too complicated to use.
> > 
> > One advantage would be that we can reuse the uio framework
> > for the devices themselves. So an existing app can just program
> > an iommu for DMA and keep using uio for interrupts and access.
> 
> The driver is called UIO and not U-INTR-MMIO ;-) So I think handling
> IOMMU mappings belongs there.

Maybe it could be put there but the patch posted did not use uio.
And one of the reasons is that uio framework provides for
device access and interrupts but not for programming memory mappings.

Solutions (besides giving up on uio completely)
could include extending the framework in some way
(which was tried, but the result was not pretty) or adding
a separate driver for iommu and binding to that.

-- 
MST
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