Re: [dpdk-dev] [RFC] Wireless Base Band Device (bbdev)

[Flavio Leitner <fbl@redhat.com>]

On Tue, 03 Oct 2017 17:17:53 +0200
Thomas Monjalon <thomas@monjalon.net> wrote:

> 03/10/2017 16:29, Mokhtar, Amr:
> > From: Thomas Monjalon [mailto:thomas@monjalon.net]  
> > > 25/08/2017 15:46, Amr Mokhtar:  
> > > > +int
> > > > +rte_bbdev_configure(uint8_t dev_id, uint16_t num_queues,
> > > > +		const struct rte_bbdev_conf *conf);  
> > > 
> > > I am not convinced by the "configure all" function in ethdev.
> > > We break the ABI each time we add a new feature to configure.
> > > And it does not really help to have all configurations in one struct.
> > > Would you mind to split the struct rte_bbdev_conf and split the function
> > > accordingly?  
> > 
> > There is nothing to split tbh. The only parameter it has is the socket_id.
> > And in fact, it's optional, can be null. The only config we need is num_queues.  
> 
> Indeed, there is nothing in this struct.
> If you need only to allocate queues, you just have to rename this function.
> 
> > I don't see in the near future that we may need to add more config params.
> > As a side, in the time of the implementation we were trying to avoid any
> > diversions from the current design ideology of ethdev and cryptodev.  
> 
> There is no ideology in ethdev, just some mistakes ;)
> 
> > Can we leave it for consideration with future releases?  
> 
> No it should be addressed from the beginning.
> 
> When you will need to add something more to configure port-wise,
> you should add a new function instead of breaking the ABI
> of the global conf struct.
> That's why the configure option should be more specialized.
> 
> Distro people were complaining about ABI breakage last week.
> This is exactly an example of how to avoid it from the beginning.

Exactly, and fixing in future is unlikely to happen or could be
more difficult and even if it happens, it will cause another breakage.

-- 
Flavio