[dpdk-users] DPDK KNI last 4 bytes of a frame truncated

[dpdk-users] DPDK KNI last 4 bytes of a frame truncated

[Pavan Kumar]

Hi,

I am trying to run example KNI application on Intel 82599ES 10-Gigabit. I see that the last 4 bytes of the frame are always truncated.
I did a quick dump of frame length in kni_ingress ().

pkts_burst[i]->pkt_len  = 268 bytes (Actual frame length from source is 272 bytes)

I did a ip4 typecast of the received mbuf, it shows ip4->total_length is 254, which is 4 bytes less than actual data I send. Below is the sample code I used to dump ipv4 frame length.

if (rte_be_to_cpu_16(ether_type) == ETHER_TYPE_IPv4) {
            ip4 = rte_pktmbuf_mtod_offset(mbuf, struct ipv4_hdr *, hdr_len);
            hdr_len += sizeof(struct ipv4_hdr);
            l4_proto = ip4->next_proto_id;
            printf ("ip pkt len %d\n", rte_be_to_cpu_16(ip4->total_length));
}

I came across a similar post/ release notes for I350 controller (Ref: IXA00372461) which says CRC stripping is always enabled and results in last 4 byte loss.
Is this a similar problem I am facing for 10G 82599 NIC using KNI ?

Thanks
Pavan

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