Re: [dpdk-dev] [PATCH v5 2/3] mbuf:add three TX ol_flags and repalce PKT_TX_VXLAN_CKSUM

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

Hi Konstantin,

On 12/03/2014 01:59 PM, Ananyev, Konstantin wrote:
>> I still think having a flag IPV4 + another flag IP_CHECKSUM is not
>> appropriate.
>
> Sorry, didn't get you here.
> Are you talking about our discussion should PKT_TX_IP_CKSUM and PKT_TX_IPV4 be mutually exclusive or not?

Yes

>> I though Konstantin agreed on other flags, but I may
>> have misunderstood:
>>
>> http://dpdk.org/ml/archives/dev/2014-November/009070.html
>
> In that mail, I was talking about my suggestion to make  PKT_TX_IP_CKSUM, PKT_TX_IPV4 and PKT_TX_IPV6 to occupy 2 bits.
> Something like:
> #define	PKT_TX_IP_CKSUM	(1 << X)
> #define	PKT_TX_IPV6		(2 << X)
> #define 	PKT_TX_IPV4		(3 << X)
>
> "Even better, if we can squeeze these 3 flags into 2 bits.
> Would save us 2 bits, plus might be handy, as in the PMD you can do:
>
> switch (ol_flags & TX_L3_MASK) {
>      case TX_IPV4:
>         ...
>         break;
>      case TX_IPV6:
>         ...
>         break;
>      case TX_IP_CKSUM:
>         ...
>         break;
> }"
>
> As you pointed out, it will break backward compatibility.
> I agreed with that and self-NACKed it.

ok, so we are back between:

1/ (Jijiang's patch)
PKT_TX_IP_CKSUM  /* packet is IPv4, and we want hw cksum */
PKT_TX_IPV6      /* packet is IPv6 */
PKT_TX_IPV4      /* packet is IPv4, and we don't want hw cksum */

with PKT_TX_IP_CKSUM and PKT_TX_IPV4 exclusive

and

2/
PKT_TX_IP_CKSUM  /* we want hw IP cksum */
PKT_TX_IPV6      /* packet is IPv6 */
PKT_TX_IPV4      /* packet is IPv4 */

with PKT_TX_IP_CKSUM implies PKT_TX_IPV4


Solution 2/ looks better from a user point of view. Anyone else has an
opinion?

Regards,
Olivier