[dpdk-dev] Wrong TCP Checkum computed by hardware

[Padam Jeet Singh]

> On 28-Oct-2015, at 1:31 pm, Liu, Jijiang <jijiang.liu at intel.com> wrote:
> 
> 
>> -----Original Message-----
>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Padam Jeet Singh
>> Sent: Wednesday, October 28, 2015 3:20 PM
>> To: Matthew Hall
>> Cc: dev at dpdk.org
>> Subject: Re: [dpdk-dev] Wrong TCP Checkum computed by hardware
>> 
> 
> Did you set the txq_flags?
> If the flag is not set, the default value is IXGBE_SIMPLE_FLAGS, and the any TX offloads do not work.
> 
> See the following codes in ixgbe_rxtx.c file
> 
> /* Use a simple Tx queue (no offloads, no multi segs) if possible */
> 	if (((txq->txq_flags & IXGBE_SIMPLE_FLAGS) == IXGBE_SIMPLE_FLAGS)
> 			&& (txq->tx_rs_thresh >= RTE_PMD_IXGBE_TX_MAX_BURST)) {
> 		PMD_INIT_LOG(INFO, "Using simple tx code path");
>                      ...
> 		dev->tx_pkt_burst = ixgbe_xmit_pkts_simple;
> 	} else {
> 	             ...
> 		dev->tx_pkt_burst = ixgbe_xmit_pkts;
> 	}
> 
> 
> --Jijiang Liu

I initialise the queue with the following structure:

static const struct rte_eth_txconf tx_conf = {
	.tx_thresh = {
		.pthresh = 32,  /* Ring prefetch threshold */
		.hthresh = 0,   /* Ring host threshold */
		.wthresh = 0,   /* Ring writeback threshold */
	},
	.tx_free_thresh = 0,    /* Use PMD default values */
	.tx_rs_thresh = 0,      /* Use PMD default values */
};

This would set the txq_flags to zero - so the tx_pkt_burst function would always point to ixgbe_xmit_pkts. Also, as observed only TCP checksum is computed wrong when there is VLAN TX Offload + IP Offload + TCP offload bits set.  VLAN TX Offload + IP Offload + TCP CKSUM in software generates correct packet on the wire.

Thanks,
Padam