Re: Running DPDK as an unprivileged user

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 02 Jan 2017 15:32:08 +0100
Thomas Monjalon <thomas.monjalon@6wind.com> wrote:

> 2016-12-29 17:14, Stephen Hemminger:
> > On Thu, 29 Dec 2016 20:41:21 +0000
> > "Walker, Benjamin" <benjamin.walker@intel.com> wrote:  
> > > My second question is whether the user should be allowed to
> > > mix uio and vfio usage simultaneously. For vfio, the
> > > physical addresses are really DMA addresses and are best
> > > when arbitrarily chosen to appear sequential relative to
> > > their virtual addresses. For uio, they are physical
> > > addresses and are not chosen at all. It seems that these two
> > > things are in conflict and that it will be difficult, ugly,
> > > and maybe impossible to resolve the simultaneous use of
> > > both.  
> > 
> > Unless application is running as privileged user (ie root), UIO
> > is not going to work. Therefore don't worry about mixed environment.  
> 
> Yes, mixing UIO and VFIO is possible only as root.
> However, what is the benefit of mixing them?

One possible case where this could be used, Hyper-V/Azure and SR-IOV.
The VF interface will show up on an isolated PCI bus and the virtual NIC
is on VMBUS. It is possible to use VFIO on the PCI to get MSI-X per queue
interrupts, but there is no support for VFIO on VMBUS.