Re: [dpdk-dev] Byte order of vlan_tci of rte_mbuf is different on different source

[Roger B Melton <rmelton@cisco.com>]

Hi folks,

Resurrecting this old thread.  I ran across this issue recently in DPDK 
17.05, and it's also present in17.08.  It appears no fix was committed.  
I'm working on a solution, but if anyone has a fix in flight please let 
me know.

Regards,
Roger


On 4/29/16 3:29 AM, Olivier Matz wrote:
> Hi,
>
> On 04/25/2016 04:35 AM, zhang.xinghua1@zte.com.cn wrote:
>> When using I350 working on SR-IOV mode, we got confused that byte order
>> of vlan_tci in the VF received packet descriptor is different when the
>> packet source is different.
>>
>> 1) Packets from VF to VF, the byte order is big-endian. (e.g. 0xF00)
>> 2) Packets from PC to VF, the byte order is little-endian. (e.g. 0xF)
>>
>> Below is the testing net-work:
>>          VM0            VM1             PC
>>          VF0            VF1              |
>>            |             |               |
>>            +------+------+               |
>>                   |                      |
>>                   PF                     |
>>               hypervisor                 |
>>               SR-IOV NIC                 |
>>                   |                      |
>>                   |        VLAN 15       |
>>                   +---------switch-------+
>>
>>
>> We make a breakpoint at the following line of eth_igb_recv_pkts, the
>> vlan_tci
>> we observed that everytime.
>>
>> uint16_t
>> eth_igb_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
>>                 uint16_t nb_pkts)
>>
>>                  /* Only valid if PKT_RX_VLAN_PKT set in pkt_flags */
>>                  rxm->vlan_tci = rte_le_to_cpu_16(rxd.wb.upper.vlan);
> In rte_mbuf.h, it is specified that these values (vlan_tci and
> vlan_tci_outer) must be stored in CPU order.
>
> It's probably a driver or hardware issue. Note that in linux there is
> something that looks similar to your issue:
>
> http://lxr.free-electrons.com/source/drivers/net/ethernet/intel/igb/igb_main.c#L1278
>
>        /* On i350, i354, i210, and i211, loopback VLAN packets
>         * have the tag byte-swapped.
>         */
>        if (adapter->hw.mac.type >= e1000_i350)
>            set_bit(IGB_RING_FLAG_RX_LB_VLAN_BSWAP, &ring->flags);
>
> I think you could check if the same thing is done in the
> dpdk driver.
>
>
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> Regards,
> Olivier
> .
>