[dpdk-dev] [PATCH v3 03/10] net/enic: heed the requested max Rx packet size

[Hyong Youb Kim]

On Fri, Mar 09, 2018 at 03:57:46PM +0000, Ferruh Yigit wrote:
> On 3/9/2018 3:51 PM, Ananyev, Konstantin wrote:
[...]
> >> Is this work based on an application that uses max_rx_pkt_len and to make PMD
> >> compatible with that application? If so we can continue with patch, but if the
> >> patch is to implement DPDK properly I suggest postponing this until
> >> max_rx_pkt_len clarified.
> >>
> >> [1]
> >> https://dpdk.org/ml/archives/dev/2018-March/092178.html
> > 
> > I think there are quite a lot apps these days that might rely on setting MTU via
> > rxmode.max_rx_pkt_len.
> > I think we need to support them till we (ever) deprecate rxmode.max_rx_pkt_len.
> 
> Right. I was trying to save effort in case something changes related
> max_rx_pkt_len, but since it is not clear yet, will continue with this patch.
> 
> > Konstantin
> > 

testpmd has a command to change max_rx_pkt_len, a few DTS test cases
rely on this feature to see if packets of certain sizes get dropped,
and so on. We worked on this patch to support these cases.

I prefer using only MTU, to follow the convention of most (all?)
OSes. Though, this feature (max_rx_pkt_len) seems to come straight
from an Intel 82599 feature. In its datasheet, see "8.2.3.22.13 Max
Frame Size -- MAXFRS". Like to understand use cases for that, if
anyone can share.

-Hyong