From mboxrd@z Thu Jan  1 00:00:00 1970
From: Chas Williams <3chas3@gmail.com>
Subject: MTU vs MRU
Date: Tue, 25 Sep 2018 20:38:34 -0400
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What does (or should) rte_eth_dev_set_mtu() do?  The documentation says
"Change the MTU of an Ethernet device."  At least of few of the PMDs do
something similar to the following:

         eth_em_infos_get(dev, &dev_info);
         frame_size = mtu + ETHER_HDR_LEN + ETHER_CRC_LEN + ...

         /* check that mtu is within the allowed range */
         if ((mtu < ETHER_MIN_MTU) || (frame_size > dev_info.max_rx_pktlen))
                 return -EINVAL;

         /* update max frame size */
         dev->data->dev_conf.rxmode.max_rx_pkt_len = frame_size;

What does max_rx_pkt_len mean here?  MRU or is pkt here really frame?