Re: [dpdk-dev] [PATCH v3 08/13] testpmd: rework csum forward engine

[Olivier MATZ <olivier.matz@6wind.com>]

Hi Konstantin,

On 11/26/2014 01:25 PM, Ananyev, Konstantin wrote:
>> By the way (this is probably off-topic), but I'm wondering if the TX
>> flags should have the same values than the RX flags:
>>
>>     #define PKT_TX_IPV4          PKT_RX_IPV4_HDR
>>     #define PKT_TX_IPV6          PKT_RX_IPV6_HDR
>
> Thought about that too.
>  From one side,  it is a bit out of our concept: separate RX and TX falgs.
>  From other side, it allows us to save 2 bits in the ol_flags.
> Don't have any strong opinion here.
> What do you think?

I have no strong opinion too, but I have a preference for 2 different
bit values for these flags:

- as you say, it's matches the concept (RX and TX flags are separated)

- 64 bits is a lot, we have some time before there is no more available
   bit... and I hope we it will never occur because it would become
   complex for an application to handle them all

- it will avoid to send a packet with a bad info:
   - we receive a Ether/IP6/IP4/L4/data packet
   - the driver sets PKT_RX_IPV6_HDR
   - the stack decapsulates IP6
   - the stack sends the packet, it has the PKT_TX_IPV6 flag but it's an
     IPv4 packet

   This is not a real problem as the flag will not be used by the
   driver/hardware (it's only mandatory for hw cksum / tso), but
   it can be confusing.

Regards,
Olivier