[RFC PATCH v3] ethdev: support selective Rx data

[Etelson, Gregory]

Hello,

>> In some cases application does not need to receive entire packet
>> from port hardware.
>
> Which scenarios need to be used?

A typical use case for the selective Rx data read can be the SAMPLE flow action.
In that scenario, Rx queue that receives sampled packet copy can be configured 
to deliver to application partial packet data.

> What is the behavior when
> LRO(TCP packet aggregation is performed by hardware) is enabled?
>

The selective Rx data read is applied to MBUF layout that will be delivered to 
an application.
That functionality comes after all HW Rx offloads.

Regards,
Gregory