RE: [PATCH net-next v2 4/7] devlink: allow subports on devlink PCI ports

[Parav Pandit <parav@mellanox.com>]

> -----Original Message-----
> From: Jiri Pirko <jiri@resnulli.us>
> Sent: Friday, March 22, 2019 11:28 AM
> To: Parav Pandit <parav@mellanox.com>
> Cc: Jakub Kicinski <jakub.kicinski@netronome.com>; Samudrala, Sridhar
> <sridhar.samudrala@intel.com>; davem@davemloft.net;
> netdev@vger.kernel.org; oss-drivers@netronome.com
> Subject: Re: [PATCH net-next v2 4/7] devlink: allow subports on devlink PCI
> ports
> 
> Thu, Mar 21, 2019 at 06:34:22PM CET, parav@mellanox.com wrote:
> >
> >
> >> -----Original Message-----
> >> From: Jiri Pirko <jiri@resnulli.us>
> >> Sent: Thursday, March 21, 2019 12:21 PM
> >> To: Parav Pandit <parav@mellanox.com>
> >> Cc: Jakub Kicinski <jakub.kicinski@netronome.com>; Samudrala, Sridhar
> >> <sridhar.samudrala@intel.com>; davem@davemloft.net;
> >> netdev@vger.kernel.org; oss-drivers@netronome.com
> >> Subject: Re: [PATCH net-next v2 4/7] devlink: allow subports on
> >> devlink PCI ports
> >>
> >> Thu, Mar 21, 2019 at 05:52:09PM CET, parav@mellanox.com wrote:
> >> >
> >> >
> >> >> -----Original Message-----
> >> >> From: Jiri Pirko <jiri@resnulli.us>
> >> >> Sent: Thursday, March 21, 2019 11:14 AM
> >> >> To: Parav Pandit <parav@mellanox.com>
> >> >> Cc: Jakub Kicinski <jakub.kicinski@netronome.com>; Samudrala,
> >> >> Sridhar <sridhar.samudrala@intel.com>; davem@davemloft.net;
> >> >> netdev@vger.kernel.org; oss-drivers@netronome.com
> >> >> Subject: Re: [PATCH net-next v2 4/7] devlink: allow subports on
> >> >> devlink PCI ports
> >> >>
> >> >> Thu, Mar 21, 2019 at 04:14:53PM CET, parav@mellanox.com wrote:
> >> >> >
> >> >> >
> >> >> >> -----Original Message-----
> >> >> >> From: Jiri Pirko <jiri@resnulli.us>
> >> >> >> Sent: Thursday, March 21, 2019 3:45 AM
> >> >> >> To: Jakub Kicinski <jakub.kicinski@netronome.com>
> >> >> >> Cc: Parav Pandit <parav@mellanox.com>; Samudrala, Sridhar
> >> >> >> <sridhar.samudrala@intel.com>; davem@davemloft.net;
> >> >> >> netdev@vger.kernel.org; oss-drivers@netronome.com
> >> >> >> Subject: Re: [PATCH net-next v2 4/7] devlink: allow subports on
> >> >> >> devlink PCI ports
> >> >> >>
> >> >> >> Mon, Mar 18, 2019 at 08:16:42PM CET,
> >> >> >> jakub.kicinski@netronome.com
> >> >> >> wrote:
> >> >> >> >On Mon, 18 Mar 2019 13:11:54 +0100, Jiri Pirko wrote:
> >> >> >> >> >> >2. flavour should not be vf/pf, flavour should be
> >> >> >> >> >> >hostport,
> >> >> switchport.
> >> >> >> >> >> >Because switch is flat and agnostic of pf/vf/mdev.
> >> >> >> >> >>
> >> >> >> >> >> Not sure. It's good to have this kind of visibility.
> >> >> >> >> >
> >> >> >> >> >Yes, this subthread honestly makes me go from 60% sure to
> >> >> >> >> >95% sure we shouldn't do the dual object thing :(  Seems
> >> >> >> >> >like Parav is already confused by it and suggests host port
> >> >> >> >> >can exist without switch port :(
> >> >> >> >>
> >> >> >> >> Although I understand your hesitation, the host ports are
> >> >> >> >> also associated with the asic and should be under the devlink
> instance.
> >> >> >> >> It is just a matter of proper documentation and clear code
> >> >> >> >> to avoid confusions.
> >> >> >> >
> >> >> >> >They are certainly a part and belong to the ASIC, the question
> >> >> >> >in my mind is more along the lines of do we want "one pipe/one
> port"
> >> >> >> >or is it okay to have multiple software objects of the same
> >> >> >> >kind for those objects.
> >> >> >> >
> >> >> >> >To put it differently - do want a port object for each port of
> >> >> >> >the ASIC or do we want a port object for each netdev..
> >> >> >>
> >> >> >> Perhaps "port" name of the object is misleading. From the
> >> >> >> beginning, I ment to have it for both switch ports and host ports.
> >> >> >> I admit that "host port" is a bit misleading, as it is not
> >> >> >> really a port of eswitch, but the counter part. But if we
> >> >> >> introduce another object for that purpose in devlink (like
> >> >> >> "partititon"), it would be a lot of duplication
> >> >> I think.
> >> >> >>
> >> >> >> Question is, do we need the "host port"? Can't we just put a
> >> >> >> relation to host netdev in the eswitch port.
> >> >> >>
> >> >> >Can you please explain how does it work for rdma for non sriov
> >> >> >use
> >> case?
> >> >> >Do we have to create a fake eswitch object?
> >> >>
> >> >> Could you please provide details on "rdma for non sriov use case"?
> >> >>
> >> >There are multiple mdevs on PFs that happen to have link layer as IB
> >> >and
> >> those devlink instances have port that deserved to be configured same
> >> way as that of Eth.
> >>
> >> Could you please describe it a bit more. There is still an eswitch
> >> through which the traffic is going, isn't it?
> >Yes, there is an eswitch but it doesn't have switch side of vports.
> 
> Why? They should have.
> 
It doesn't have.

> 
> >It is equivalent to legacy mode.
> >I hope you are not thinking to create fake eswitch vports. :-)