[dpdk-dev] [PATCH] net/ring: advertise multi segment support.

[Dumitru Ceara]

On 9/22/20 4:21 PM, Ferruh Yigit wrote:
> On 9/18/2020 11:36 AM, Dumitru Ceara wrote:
>> Even though ring interfaces don't support any other TX/RX offloads they
>> do support sending multi segment packets and this should be advertised
>> in order to not break applications that use ring interfaces.
>>
> 
> Does ring PMD support sending multi segmented packets?
> 

Yes, sending multi segmented packets works fine with ring PMD.

> As far as I can see ring PMD doesn't know about the mbuf segments.
> 

Right, the PMD doesn't care about the mbuf segments but it implicitly
supports sending multi segmented packets. From what I see it's actually
the case for most of the PMDs, in the sense that most don't even check
the DEV_TX_OFFLOAD_MULTI_SEGS flag and if the application sends multi
segment packets they are just accepted.

However, the fact that the ring PMD doesn't advertise this implicit
support forces applications that use ring PMD to have a special case for
handling ring interfaces. If the ring PMD would advertise
DEV_TX_OFFLOAD_MULTI_SEGS this would allow upper layers to be oblivious
to the type of underlying interface.

Thanks,
Dumitru