[dpdk-dev] [RFC PATCH v2 3/5] librte_ether: add API's for VF management

[Iremonger, Bernard]

<snip>

> > Subject: Re: [dpdk-dev] [RFC PATCH v2 3/5] librte_ether: add API's for
> > VF management
> >
> > 2016-09-28 13:26, Ananyev, Konstantin:
> > > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com]
> > > > 2016-09-28 11:23, Ananyev, Konstantin:
> > > > > If we  this way (force user to include driver specific headers
> > > > > and call driver specific functions), how you guys plan to make this
> functionality available for multiple driver types.
> > > >
> > > > Multiple drivers won't have exactly the same specific features.
> > > > But yes, there are some things common to several Intel NICs.
> > > >
> > > > > From discussion with Bernard  understand that customers would
> need similar functionality for i40e.
> > > > > Does it mean that they'll have to re-implement this part of their code
> again?
> > > > > Or would have to create (and maintain) their own shim layer that
> would provide some s of abstraction?
> > > > > Basically their own version of rte_ethdev?
> > > >
> > > > No definitive answer.
> > > > But we can argue the contrary: how to handle a generic API which
> > > > is implemented only in 1 or 2 drivers? If the application tries to use it,
> we can imagine that a specific range of hardware is expected.
> > >
> > > Yes, as I understand, it is a specific subset of supported HW (just Inel NICs
> for now, but different models/drivers).
> > > Obviously users would like to have an ability to run their app on all HW
> from this subset without rebuilding/implementing the app.
> > >
> > > >
> > > > I think it is an important question.
> > > > Previously we had the issue of having some API which are too
> > > > specific and need a rework to be used with other NICs. In order to
> > > > avoid such rework and API break, we can try to make them available
> > > > in a driver-specific or vendor-specific staging area, waiting for
> > a later generalization.
> > >
> > > Could you remind me why you guys were that opposed to ioctl style
> approach?
> > > It is not my favorite thing either, but it seems pretty generic way to
> handle such situations.
> >
> > We prefer having well-defined functions instead of opaque ioctl-style
> encoding.
> > And it was not clear what is the benefit of ioctl.
> > Now I think I understand you would like to have a common ioctl service for
> features available on 2 drivers. Right?
> 
> Yes.
> 
> > Example (trying to  read your mind):
> > 	rte_ethdev_ioctl(port_id, <TLV encoding VF_PING service and VF
> id>); instead of
> > 	rte_pmd_ixgbe_vf_ping(port_id, vf_id);
> > 	rte_pmd_i40e_vf_ping(port_id, vf_id); Please confirm I understand
> > what you are thinking about.
> 
> Yep, you read my mind correctly :)
> Konstantin
> 
Adding the pmd_ops field to struct eth_devops {} discussed previously in this email thread will allow driver specific functions for multiple drivers and will get rid of the driver specific header file rte_pmd_driver.h.
Would this be an acceptable solution?

Regards,

Bernard.