On 3/8/2018 2:46 AM, John Daley wrote: > From: Hyong Youb Kim <hyon...@cisco.com> > > Currently, enic completely ignores the requested max Rx packet size > (rxmode.max_rx_pkt_len). The desired behavior is that the NIC hardware > drops packets larger than the requested size, even though they are > still smaller than MTU.
Your description looks reasonable but is there reason of two levels of limits, max_rx_pkt_len and MTU, why not just use MTU. There is already a mail thread to clarify max_rx_pkt_len [1]. 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 > > Cisco VIC does not have such a feature. But, we can accomplish a > similar (not same) effect by reducing the size of posted receive > buffers. Packets larger than the posted size get truncated, and the > receive handler drops them. This is also how the kernel enic driver > enforces the Rx side MTU. > > This workaround works only when scatter mode is *not* used. When > scatter is used, there is currently no way to support > rxmode.max_rx_pkt_len, as the NIC always receives packets up to MTU. > > For posterity, add a copious amount of comments regarding the > hardware's drop/receive behavior with respect to max/current MTU. > > Signed-off-by: Hyong Youb Kim <hyon...@cisco.com> > Reviewed-by: John Daley <johnd...@cisco.com> <...>
