[dpdk-users] mlx5 driver didn't set corresponding packet_type flag in TCP_ACK packet case

[Nélio Laranjeiro]

Hi Bin,

On Mon, Mar 26, 2018 at 06:09:35PM +0800, Bin Huang wrote:
> Greetings all,
> 
> 
> I have run l3fwd example program using two mlx5 NIC(
> MLNX_OFED_LINUX-4.3-1.0.1.0 ) base on DPDK 17.08 and use pktgen as
> flowgen.
> 
> This demo provided by DPDK works fine in UDP case, but in pktgen TCP
> case, l3fwd can't forward packet to nexthop port.
> 
> 
> After look into function rxq_cq_to_pkt_type(), I found while handling
> IPv4 TCP ACK packets:
> 
> > l4_hdr_type bits[2:0] in CQE is (100)
> 
> > l3_hdr_type bits[1:0] in CQE is (10)
> 
> 
> It looks fine according to CQE format in
> <Ethernet_Adapters_Programming_Manual> doc:
> 
> > l4_hdr_type:
>     0 - None
>     1 - TCP header was present in the packet
>     2 - UDP header was present in the packet
>     3 - TCP header was present in the packet with Empty TCP ACK
> indication. (TCP packet <ACK> flag is set, and packet carries no data)
>     4 - TCP header was present in the packet with TCP ACK indication.
> (TCP packet <ACK> flag is set, and packet carries data).
> 
> > l3_hdr_type:
> 
>     00 - None
>     01 - IPv6
>     10 - IPv4
> 
> 
> But combined l4_hdr_type and l3_hdr_type into idx, the idx would be
> 0x12, which was not reserved in mlx5_set_ptype_type().
> 
> Then RTE_PTYPE_UNKNOWN would be return to caller which caused
> sub-sequence procedure going wrong.
> 
> 
> Did I omit any possible configuration to make ptype flag work for TCP
> ACK packets, or should I add (*p)[0x12] in mlx5_set_ptype_type() to
> make this work?

According to the mlx5_set_ptype_table(), the index of the array is a
little more complex:

 /*
  * The index to the array should have:
  * bit[1:0] = l3_hdr_type
  * bit[4:2] = l4_hdr_type
  * bit[5] = ip_frag
  * bit[6] = tunneled
  * bit[7] = outer_l3_type
  */

If in the CQE the other three fields are 0, your hypothesis is correct
and index 0x12 should be filled.

Can you also check it?

> Thanks for your time,
> 
> Bin

Thanks,

-- 
Nélio Laranjeiro
6WIND