RE: [RFC net-next v1 0/3] Support mlx5 mediated devices in host

[Parav Pandit]

Hi Jakub,

> -----Original Message-----
> From: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
> Sent: Wednesday, March 13, 2019 5:08 PM
> To: Parav Pandit <parav@xxxxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> michal.lkml@xxxxxxxxxxx; davem@xxxxxxxxxxxxx;
> gregkh@xxxxxxxxxxxxxxxxxxx; Jiri Pirko <jiri@xxxxxxxxxxxx>;
> kwankhede@xxxxxxxxxx; alex.williamson@xxxxxxxxxx; Vu Pham
> <vuhuong@xxxxxxxxxxxx>; Yuval Avnery <yuvalav@xxxxxxxxxxxx>;
> kvm@xxxxxxxxxxxxxxx
> Subject: Re: [RFC net-next v1 0/3] Support mlx5 mediated devices in host
> 
> On Fri,  8 Mar 2019 16:07:53 -0600, Parav Pandit wrote:
> > Use case:
> > ---------
> > A user wants to create/delete hardware linked sub devices without
> > using SR-IOV.
> > These devices for a pci device can be netdev (optional rdma device) or
> > other devices. Such sub devices share some of the PCI device resources
> > and also have their own dedicated resources.
> > A user wants to use this device in a host where PF PCI device exist.
> > (not in a guest VM.) A user may want to use such sub device in future
> > in guest VM.
> >
> > Few examples are:
> > 1. netdev having its own txq(s), rq(s) and/or hw offload parameters.
> > 2. netdev with switchdev mode using netdev representor
> 
> Hi Parav!
> 
> Sorry for going quiet, I'm hoping to clarify the use cases and the devlink part
> on the other thread with Jiri, and then come back to implementation details.
> 
That's fine. Now we have detached two things so we don't need to create mediated devices etc through devlink anymore.
It is not just implementation details here in RFC.
RFC describes the single and multiport use cases and attachment with devlink too.
It uses existing well defined devlink objects.
So I am not envisioning a big change.

> > 3. rdma device with IB link layer and IPoIB netdev 4. rdma/RoCE device
> > and a netdev 5. rdma device with multiple ports