[dpdk-dev] [RFC 00/14] mlx5: support SubFunction

[Xia, Chenbo]

Hi Parav,

> -----Original Message-----
> From: Parav Pandit <parav at nvidia.com>
> Sent: Tuesday, June 15, 2021 12:05 PM
> To: Xia, Chenbo <chenbo.xia at intel.com>; NBU-Contact-Thomas Monjalon
> <thomas at monjalon.net>; Yigit, Ferruh <ferruh.yigit at intel.com>
> Cc: Xueming(Steven) Li <xuemingl at nvidia.com>; Slava Ovsiienko
> <viacheslavo at nvidia.com>; dev at dpdk.org; Jason Gunthorpe <jgg at nvidia.com>
> Subject: RE: [dpdk-dev] [RFC 00/14] mlx5: support SubFunction
> 
> Hi Chenbo,
> 
> > From: Xia, Chenbo <chenbo.xia at intel.com>
> > Sent: Tuesday, June 15, 2021 7:41 AM
> >
> > Hi Thomas,
> >
> > > From: Thomas Monjalon <thomas at monjalon.net>
> > > Sent: Friday, June 11, 2021 3:54 PM
> [..]
> 
> >
> > Yes. In our term it's called Assignable Device Interface (ADI) introduced in
> > Intel Scalable IOV (https://01.org/blogs/2019/assignable-interfaces-intel-
> > scalable-i/o-virtualization-linux)
> >
> > And vfio-mdev is chosen to be the software framework for it. I start to
> realize
> > there is difference between SF and ADI: SF considers multi-function devices
> > which may include net/regex/vdpa/...
> Yes. net, rdma, vdpa, regex ++.
> And eventually vfio_device to map to VM too.
> 
> Non mdev framework is chosen so that all the use cases of kernel only, or user
> only or mix modes can be supported.

OK. Got it.

> 
> > But ADI only focuses on the
> > virtualization of the devices and splitting devices to logic parts and
> providing
> > huge number of interfaces to host APP. I think SF also considers this but is
> > mainly used for multi-function devices (like DPU in your term?
> > Correct me if I'm wrong).
> >
> SF also supports DPU mode too but it is in addition to above use cases.
> SF will expose mdev (or a vfio_device) to map to a VM.

So your SW actually supports vfio-mdev? I suppose the device-specific mdev
Kernel module is out-of-tree?

Just FYI:

We are introducing a new mdev bus for DPDK:
http://patchwork.dpdk.org/project/dpdk/cover/20210601030644.3318-1-chenbo.xia@intel.com/

Thanks,
Chenbo

> 
> > And I also noticed that the mdev-based interface can only be used in
> > userspace but aux-based interface can also be used by other kernel sub-
> > system (like for net, wrap it as netdev).
> Correct.