[dpdk-dev] vfio: failed to select IOMMU type

Alejandro Lucero alejandro.lucero at netronome.com
Tue Apr 18 13:22:07 CEST 2017

On Thu, Apr 6, 2017 at 11:10 AM, Burakov, Anatoly <anatoly.burakov at intel.com
> wrote:

> Hi Alejandro,
> > Yes, the code was not aware of that possibility. Being honest, I knew
> about that, but not in my mind when implementing the code. I have just
> cards where each PF even VF have their own VFIO group. This could be a
> problem for testing.
> > Anatoly, do you have a system with that peculiarity?
> I think if you compile an old kernel (like a 3.6), you should be able to
> reproduce the behavior. (at least I am able to do this with an old kernel)
It turns out the container is not removed while it has users, and having a
group file descriptor opened implies an active user. So we need another
approach. The kernel does not give any information we can use (and maybe it
requires a patch for fixing a potential problem regarding group closing)
but we can track number of devices in a group easily and close the group
when last device is closed.

I have tested this approach and it works for the single device per group
case, which is the one I can test by now. But I'm not sure I understood
this comment about using a old kernel for testing the multiple devices per
group case. Can you confirm if I understood this correctly? If I use an old
kernel, devices like VFs are created in the same IOMMU group?


> Thanks,
> Anatoly

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