Re: [dpdk-dev] [PATCH v3] ether: use a default for max Rx frame size in configure()

[Thomas Monjalon <thomas@monjalon.net>]

07/04/2017 17:27, Andriy Berestovskyy:
> Hey Thomas,
> 
> On 07.04.2017 16:47, Thomas Monjalon wrote:
> >> What if we add to the max_rx_pkt_len description: "the effective maximum
> >> RX frame size depends on PMD, please refer the PMD guide for the
> >> details"?
> > 
> > I think the problem is not in the documentation but in the implementations
> > which should be more consistent.
> 
> The hardware is different, there is not much we can do about it.

We can return an error if the max_rx_pkt_len cannot be set in the NIC.

> Nevertheless, we can fix the false comment and have a default for the
> jumbos, which is beneficial for the apps/examples.

The examples are using a hardcoded value, so they need to be fixed anyway.

> > If I understand well, the inconsistency between drivers was already an
> > issue before your patch.
> > Your patch fixes an inconsistency in ethdev without fixing the drivers.
> > We need to know if it is a good first step and if the drivers can be
> > fixed later.
> 
> Thomas, some of the examples use a hard-coded jumbo frame size, which is
> too big for the underlaying PMDs, so those examples fail. The plan was
> to fix them all with this commit in ethdev but I am not sure now you are
> to accept the change.

This ethdev patch is about a behaviour change of the API.
It is about considering 0 as a request for default value
and return an error if a value cannot be set.
It will require more agreements and changes in the drivers
for returning an error where appropriate.

> It is important for us to have those examples working in the upcoming
> release, do you think it is better to send fixes for those examples
> instead of this commit then?

The examples can be improved independently of this patch.