Re: [dpdk-dev] [PATCH v7 1/1] app/testpmd: fix max rx packet length for VLAN packets

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 10/28/2020 3:03 AM, SteveX Yang wrote:
> When the max rx packet length is smaller than the sum of mtu size and
> ether overhead size, it should be enlarged, otherwise the VLAN packets
> will be dropped.
> 
> Fixes: 35b2d13fd6fd ("net: add rte prefix to ether defines")
> 
> Signed-off-by: SteveX Yang <stevex.yang@intel.com>
> ---
>   app/test-pmd/testpmd.c | 20 ++++++++++++++++++++
>   1 file changed, 20 insertions(+)
> 
> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
> index 33fc0fddf..754066950 100644
> --- a/app/test-pmd/testpmd.c
> +++ b/app/test-pmd/testpmd.c
> @@ -1421,6 +1421,7 @@ init_config(void)
>   	struct rte_gro_param gro_param;
>   	uint32_t gso_types;
>   	uint16_t data_size;
> +	uint16_t overhead_len;
>   	bool warning = 0;
>   	int k;
>   	int ret;
> @@ -1457,6 +1458,25 @@ init_config(void)
>   			rte_exit(EXIT_FAILURE,
>   				 "rte_eth_dev_info_get() failed\n");
>   
> +		/* Update the max_rx_pkt_len to have MTU as RTE_ETHER_MTU */
> +		if (port->dev_info.max_rx_pktlen && port->dev_info.max_mtu)
> +			overhead_len = port->dev_info.max_rx_pktlen -
> +				port->dev_info.max_mtu;
> +		else
> +			overhead_len = RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN;
> +
> +		port->dev_conf.rxmode.max_rx_pkt_len =
> +						RTE_ETHER_MTU + overhead_len;
> +
> +		/*
> +		 * Workaround: only adapt to RTE_ETHER_MAX_LEN as
> +		 * jumbo frame condition.
> +		 */
> +		if (port->dev_conf.rxmode.max_rx_pkt_len > RTE_ETHER_MAX_LEN) {
> +			port->dev_conf.rxmode.offloads |=
> +						DEV_RX_OFFLOAD_JUMBO_FRAME;
> +		}

I think this jumbo frame set can be dropped, above just set the frame size as 
"RTE_ETHER_MTU + overhead_len", so it can't be jumbo frame, right?