[dpdk-dev] [RFC v2] meter: fix ABI break due to experimental tag removal

[Eelco Chaudron]

On 30 Jan 2020, at 17:04, Luca Boccassi wrote:

> On Thu, 2020-01-30 at 16:55 +0100, Thomas Monjalon wrote:
>> 30/01/2020 15:21, Luca Boccassi:
>>> On Thu, 2020-01-30 at 15:17 +0100, Thomas Monjalon wrote:
>>>> 30/01/2020 13:57, Luca Boccassi:
>>>>> On Thu, 2020-01-30 at 13:33 +0100, Thomas Monjalon wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I disagree with the need of this patch.
>>>>>> The symbol was experimental, meaning we can change it.
>>>>>> Removing experimental tag is not an ABI break.
>>>>>
>>>>> Hi,
>>>>>
>>>>> This symbol change was requested for backport in 19.11.x, and
>>>>> experimental or not I'm not too keen on backward incompatible
>>>>> changes
>>>>> to the public interface in an _LTS point release_. The
>>>>> compromise
>>>>> was
>>>>> to see if we could support both symbols version, which makes
>>>>> the
>>>>> change
>>>>> backward compatible.
>>>>>
>>>>> If you prefer not to have this patch in mainline I'm also fine
>>>>> in
>>>>> taking it just for the LTS. I agree with you that it is not
>>>>> required
>>>>> for mainline releases (although nicer for me if it's a backport
>>>>> rather
>>>>> than a new change).
>>>>
>>>> I would like to avoid opening the door for maintaining the
>>>> experimental ABI
>>>> in the mainline. Please take it directly in the LTS.
>>>>
>>>> The next question is to know whether we really want to have such
>>>> patch in LTS.
>>>> Anyway, 19.11.0 has this symbol as experimental.
>>>> How adding a non-experimental version of the function in 19.11.1
>>>> will
>>>> change
>>>> the ABI status of the whole 19.11 branch?
>>>
>>> The problem is not adding the new symbol, but removing the
>>> experimental
>>> one. Changing the version of the symbol was requested by OVS for
>>> inclusion in 19.11.
>>
>> Yes, sorry, this is what I meant.
>> Given 19.11.0 already has the symbol as experimental,
>> and that applications like OVS had to accept it as experimental,
>> why removing experimental tag in 19.11.1?
>
> I think it was mentioned that it was preferred not to suppress the
> compiler warning to avoid any accidental use in the future, but the 
> OVS
> maintainer(s) should answer as I might remember wrongly.

Yes this is the reason, OVS compiles with -Werror so we would like to 
avoid the warnings. You can not disable them per include, it’s global 
for all of DPDK.

//Eelco