On Wed, Dec 16, 2015 at 12:38 PM, Alex Williamson
[off-list ref] wrote:

So it works.  Is it acceptable?  Useful?  Sufficiently complete?  Does
it imply deprecating the uio interface?  I believe the feature that
started this discussion was support for MSI/X interrupts so that VFs
can support some kind of interrupt (uio only supports INTx since it
doesn't allow DMA).  Implementing that would be the ultimate test of
whether this provides dpdk with not only a more consistent interface,
but the feature dpdk wants that's missing in uio. Thanks,

Hi Alex,

Sorry for jumping in.  Just being curious, how does VFIO No-IOMMU mode
support DMA from userspace drivers?  If I understand correctly, due to
the absence of IOMMU, pcidev has to use physaddr to start a DMA
transaction, but how it is supposed to get physaddr from userspace
drivers, /proc/<pid>/pagemap or something else?


-- 
Thanks,
Jike