[dpdk-dev] VFIO no-iommu

[Jike Song]

On Wed, Dec 16, 2015 at 12:38 PM, Alex Williamson
<alex.williamson at redhat.com> 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