Re: [PATCH 0/3] i40e VXLAN TX checksum rework

[Olivier MATZ <olivier.matz-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>]

Hi Konstantin,

On 11/27/2014 04:29 PM, Ananyev, Konstantin wrote:
>> As I suggested in the TSO thread, I think the following semantics
>> is easier to understand for the user:
>>
>>    - PKT_TX_IP_CKSUM: tell the NIC to compute IP cksum
>>
>>    - PKT_TX_IPV4: tell the NIC it's an IPv4 packet. Required for L4
>>      checksum offload or TSO.
>>
>>    - PKT_TX_IPV6: tell the NIC it's an IPv6 packet. Required for L4
>>      checksum offload or TSO.
>>
>> I think it won't make a big difference in the FVL driver.
> 
> No, no big difference here, but I still think it will be a bit cleaner if all 3 flags would be nutually exclusive.
> In fact,  we can unite all 3 of them them into 2 bits,    same as we doing for L4 checksum flags.

In case of TSO, you need to set the PKT_TX_IPV4 flag.
But as suggested by Yong Wang from Vmware [1], the vmxnet3 driver could
support TSO without offloading IP checksum, so I think it's better to
have flags for (is_ipv4 or is_ipv6), and another one to ask the
ip_checksum.


> You mean a new DEV_TX_OFFLOAD_* value, right?
> Something like:  DEV_TX_OFFLOAD_UDP_TUNNEL?
> And make i40e_dev_info_get() to return it?
> Yes, forgot about it, sounds like a proper thing to do. 

Yes. I've seen that Jijiang is planning to add it in a future bug fix
patch. That's fine to me.


[1] http://dpdk.org/ml/archives/dev/2014-November/007775.html

Regards,
Olivier