[dpdk-dev] Wrong TCP Checkum computed by hardware

[Liu, Jijiang]

> -----Original Message-----
> From: Padam Jeet Singh [mailto:padam.singh at inventum.net]
> Sent: Wednesday, October 28, 2015 4:12 PM
> To: Liu, Jijiang
> Cc: dev at dpdk.org; Matthew Hall
> Subject: Re: [dpdk-dev] Wrong TCP Checkum computed by hardware
> 
> 
> > 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.

I don't think the txq_flags is 0 if you just initialized the struct rte_eth_txconf like that.

> Thanks,
> Padam