[dpdk-dev] [PATCH v2] config: disable RTE_NEXT_ABI by default

Ferruh Yigit ferruh.yigit at intel.com
Fri Oct 5 14:35:06 CEST 2018

On 10/5/2018 12:30 PM, Neil Horman wrote:
> On Fri, Oct 05, 2018 at 11:17:30AM +0100, Ferruh Yigit wrote:
>> On 10/5/2018 10:13 AM, Bruce Richardson wrote:
>>> On Thu, Oct 04, 2018 at 05:55:34PM +0200, Thomas Monjalon wrote:
>>>> 04/10/2018 17:28, Ferruh Yigit:
>>>>> On 10/4/2018 4:10 PM, Thomas Monjalon wrote:
>>>>>> 04/10/2018 17:48, Ferruh Yigit:
>>>>>>> Enabling RTE_NEXT_ABI means to enable APIs that break the ABI for
>>>>>>> the current release and these APIs are targeted for further release.
>>>>>> It seems nobody is using it in last releases.
>>>>>>> RTE_NEXT_ABI shouldn't be enabled by default.
>>>>>> The reason for having it enabled by default is that when you build DPDK
>>>>>> yourself, you probably want the latest features.
>>>>>> If packaged properly for stability, it is easy to disable it in
>>>>>> the package recipe.
>>>>> My concern was (if this has been used), user may get unstable APIs and without
>>>>> explicitly being aware of it.
>>>> I am OK with both defaults (enabled or disabled).
>>> I'd keep it as is. As said, I'm not sure it's being used right now anyway.
>> No, not used right now.
>> But I think we can use it, did you able to find chance to check:
>> https://mails.dpdk.org/archives/dev/2018-October/114372.html
>> Option D.
> Just to propose something else, We also have the ALLOW_EXPERIMENTAL_API flag
> that we IIRC default to on.  Would it be worth consolidating these two
> mechanisms into one?  Currently ALLOW_EXPERIMENTAL_API lets us flag symbols that
> are not yet stable, and it seems to work well.  It does not however let us
> simply define out structures/variables that might adversely affect the ABI.
> Would it be worth considering adding a macro (something like
> __rte_experimental_symbol()), that allows a variable/struct to be defined if
> ALLOW_EXPERIMENTAL_API is set, and squashed otherwise?

RTE_NEXT_ABI is not just for symbols.

If there a new API foo(), __rte_experimental works fine to mark it experimental.

But if there is an _existing API_

and we plan to change it to
"bar(int, int)",

to publish the change early in this release we need RTE_NEXT_ABI ifdef since
both can't exist together, so it will be used as:

Release N:

 #ifdef RTE_NEXT_ABI
 bar(int, int);

Release N + 1:

 bar(int, int);

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