RE: [PATCH v2 2/4] examples/ipsec-secgw: disable Tx chksum offload for inline

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> Enable Tx IPv4 checksum offload only when Tx inline crypto is needed.
> In other cases such as Tx Inline protocol offload, checksum computation
> is implicitly taken care by HW. The advantage of having only necessary
> offloads enabled is that Tx burst function can be as light as possible.

I am still not sure this is a right thing to do.
Could you explain what will happen for lookaside modes?
Would they always fall-back to SW cksum calculation?

> 
> Signed-off-by: Nithin Dabilpuram <ndabilpuram@marvell.com>
> ---
>  examples/ipsec-secgw/ipsec-secgw.c | 3 ---
>  examples/ipsec-secgw/sa.c          | 9 +++++++++
>  2 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/examples/ipsec-secgw/ipsec-secgw.c b/examples/ipsec-secgw/ipsec-secgw.c
> index 21abc0d..d8a9bfa 100644
> --- a/examples/ipsec-secgw/ipsec-secgw.c
> +++ b/examples/ipsec-secgw/ipsec-secgw.c
> @@ -2314,9 +2314,6 @@ port_init(uint16_t portid, uint64_t req_rx_offloads, uint64_t req_tx_offloads)
>  		local_port_conf.txmode.offloads |=
>  			RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE;
> 
> -	if (dev_info.tx_offload_capa & RTE_ETH_TX_OFFLOAD_IPV4_CKSUM)
> -		local_port_conf.txmode.offloads |= RTE_ETH_TX_OFFLOAD_IPV4_CKSUM;
> -
>  	printf("port %u configuring rx_offloads=0x%" PRIx64
>  		", tx_offloads=0x%" PRIx64 "\n",
>  		portid, local_port_conf.rxmode.offloads,
> diff --git a/examples/ipsec-secgw/sa.c b/examples/ipsec-secgw/sa.c
> index 1839ac7..b878a48 100644
> --- a/examples/ipsec-secgw/sa.c
> +++ b/examples/ipsec-secgw/sa.c
> @@ -1790,6 +1790,15 @@ sa_check_offloads(uint16_t port_id, uint64_t *rx_offloads,
>  				RTE_SECURITY_ACTION_TYPE_INLINE_PROTOCOL)
>  				&& rule->portid == port_id) {
>  			*tx_offloads |= RTE_ETH_TX_OFFLOAD_SECURITY;
> +
> +			/* Checksum offload is not needed for inline protocol as
> +			 * all processing for Outbound IPSec packets will be
> +			 * implicitly taken care and for non-IPSec packets,
> +			 * there is no need of IPv4 Checksum offload.
> +			 */
> +			if (rule_type == RTE_SECURITY_ACTION_TYPE_INLINE_CRYPTO)
> +				*tx_offloads |= RTE_ETH_TX_OFFLOAD_IPV4_CKSUM;
> +
>  			if (rule->mss)
>  				*tx_offloads |= RTE_ETH_TX_OFFLOAD_TCP_TSO;
>  		}
> --
> 2.8.4