Re: [dpdk-dev] [PATCH] net: introduce IPv4 ihl and version fields

[Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>]

On 6/10/21 12:22 PM, Olivier Matz wrote:
> Hi Gregory,
> 
> On Thu, Jun 10, 2021 at 04:10:25AM +0000, Gregory Etelson wrote:
>> Hello,
>>
>> There was no activity that patch for a long time.
>> The patch is marked as failed, but we verified failed tests and concluded that the failures can be ignored.
>> https://patchwork.dpdk.org/project/dpdk/patch/20210527152858.13312-1-getelson@nvidia.com/
>> How should I proceed with this case ?
>> Please advise.
>>
> 
> I like the idea of this patch: to me it is more convenient to access to
> these fields with a bitfield. I don't see a problem about using
> bitfields here, glibc or FreeBSD netinet/ip.h are doing the same.
> 
> However, as stated previously, this patch breaks the initialization API.

Very good point. I guess we overlooked it in a number of patches
with fix RTE flow API items to start from corresponding network
headers. We used unions there to avoid ABI breakage, but it looks
like we have broken initialization API anyway.

We should decide if initialization ABI breakage is a show-stopper
for RTE flow API items switching to use network protocol headers.

> The DPDK ABI/API policy is described here:
> http://doc.dpdk.org/guides/contributing/abi_policy.html#the-dpdk-abi-policy
> 
>>From this document:
> 
>    The API should only be changed for significant reasons, such as
>    performance enhancements. API breakages due to changes such as
>    reorganizing public structure fields for aesthetic or readability
>    purposes should be avoided.
> 
> So to follow the project policy, I think we should reject this path.
> 
> Regards,
> Olivier
>