Re: [PATCH v2 01/10] ethdev: introduce flow pre-configuration hints

[Jerin Jacob <jerinjacobk@gmail.com>]

On Mon, Jan 24, 2022 at 11:05 PM Thomas Monjalon <thomas@monjalon.net> wrote:
>
> 24/01/2022 15:36, Jerin Jacob:
> > On Tue, Jan 18, 2022 at 9:01 PM Alexander Kozyrev <akozyrev@nvidia.com> wrote:
> > > +struct rte_flow_port_attr {
> > > +       /**
> > > +        * Version of the struct layout, should be 0.
> > > +        */
> > > +       uint32_t version;
> >
> > Why version number? Across DPDK, we are using dynamic function
> > versioning, I think, that would be sufficient for ABI versioning
>
> Function versioning is not ideal when the structure is accessed
> in many places like many drivers and library functions.
>
> The idea of this version field (which can be a bitfield)
> is to update it when some new features are added,
> so the users of the struct can check if a feature is there
> before trying to use it.
> It means a bit more code in the functions, but avoid duplicating functions
> as in function versioning.
>
> Another approach was suggested by Bruce, and applied to dmadev.
> It is assuming we only add new fields at the end (no removal),
> and focus on the size of the struct.
> By passing sizeof as an extra parameter, the function knows
> which fields are OK to use.
> Example: http://code.dpdk.org/dpdk/v21.11/source/lib/dmadev/rte_dmadev.c#L476

+ @Richardson, Bruce
Either approach is fine, No strong opinion.  We can have one approach
and use it across DPDK for consistency.

>
>