08/03/2018 20:40, Neil Horman: > On Thu, Mar 08, 2018 at 05:04:01PM +0100, Thomas Monjalon wrote: > > 08/03/2018 16:35, Neil Horman: > > > On Thu, Mar 08, 2018 at 04:17:00PM +0100, Thomas Monjalon wrote: > > > > 08/03/2018 12:43, Ferruh Yigit: > > > > > On 3/8/2018 8:05 AM, Thomas Monjalon wrote: > > > > > > 07/03/2018 18:44, Ferruh Yigit: > > > > > >> After experimental API process defined do we still need > > > > > >> RTE_NEXT_ABI > > > > > >> config and process which has similar targets? > > > > > > > > > > > > They are different targets. > > > > > > Experimental API is always enabled but may be avoided by > > > > > > applications. > > > > > > Next ABI can be used to break ABI without notice and disabled to > > > > > > keep > > > > > > old ABI compatibility. It is almost never used because it is > > > > > > preferred > > > > > > to keep ABI compatibility with rte_compat macros, or wait a > > > > > > deprecation > > > > > > period after notice. > > > > > > > > > > OK, I see. > > > > > > > > > > Shouldn't we disable it by default at least? Otherwise who is not > > > > > paying > > > > > attention to this config option will get and ABI/API break. > > > > > > > > Yes I think you are right, it can be disabled by default. > > > > > > > I would agree, there seems to be overlap here, and the experimental > > > tagging can > > > cover what the NEXT_API flag is meant to do. It can be removed I think. > > > > It is not NEXT_API but NEXT_ABI. > Sorry, typo, though I'm sure you got that, since the former doesn't exist, > right? > > Why do you think it overlaps experimental API tagging? > > I assert that because the compat lib has macros to map common symbols to > version > specific ones. That is to say, if you change a data structure, you can setup > the API calls that use said structure such that version 1 or the symbol maps > to > an internal function that uses the old structure, while version 2 maps to an > internal function that uses the new symbol > > That is to say, if you're planning on introducing ABI changes, the > experimental > API tagging can be used to implement what the NEXT_ABI macro does.
It is a different usage. Experimental API tagging is for new functions. rte_compat is used to avoid breaking the ABI when changing old code. NEXT_ABI has been used in the past to disable an ABI breakage, which was not possible to mitigate with rte_compat because impacting too many functions. I am not saying that I like NEXT_ABI, but it could be useful exceptionnally.
