Re: [dpdk-dev] VFIO in setup.sh

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

> iommu groups already exist before vfio-pci is loaded.
> The whole setup process as described in the VFIO documentation, where a
> PCIe device shares an iommu group with other devices, can therefore be
> automated. Some time ago I wrote a ruby script that does exactly that
> (https://github.com/andre-richter/rVFIO/blob/master/example/pci-
> bind.rb).
> Porting it to bash should be no problem.

Makes sense to me. Maybe we could output a warning if not all devices in a group were bound to vfio-pci (and possibly list all devices that aren't bound)? IMO, the right place for such a warning would probably be dpdk_nic_bind.py though, not setup.sh.

> However, the question is if dpdk needs to cover this (corner?) case.
> I would assume that the bulk of dpdk use-cases deals with scenarios where
> the targeted NIC is the only one in its iommu group, because it is a high-
> speed NIC that is connected to a CPU-integrated PCIe-Port.
> A NIC sharing an iommu group with other devices would be most likely if it is
> behind a bridge, aka a chipset-integrated NIC or a NIC that resides in a PCIe-
> Slot that connects to the chipset. This is more common in desktop machines
> than in server grade machines.

If no other devices need to be unbound, no warnings, and no harm done :)

Thanks,
Anatoly