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

[Iremonger, Bernard]

Hi Thomas,

<snip>

> -----Original Message-----
> Subject: Re: [dpdk-dev] [RFC PATCH v2 3/5] librte_ether: add API's for VF
> management
> 
> 2016-09-28 14:48, 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?
> 
> How pmd_ops would be different of eth_devops?

There is not a lot of difference, however it would separate generic ethdev functions from driver specific functions.

Regards,

Bernard.