Re: [dpdk-dev] [PATCH v4] eal/cpuflags: add x86 based cpu flags

["Laatz, Kevin" <kevin.laatz@intel.com>]

> On 27/04/2020 10:31, Laatz, Kevin wrote:
> >
> >> (replying this time to the list)
> >>
> >> On 25/04/2020 17:04, Thomas Monjalon wrote:
> >>> 16/04/2020 13:00, Kevin Laatz:
> >>>> This patch adds CPU flags which will enable the detection of ISA
> >>>> features available on more recent x86 based CPUs.
> >>> [...]
> >>>> --- a/devtools/libabigail.abignore
> >>>> +++ b/devtools/libabigail.abignore
> >>>> +; Ignore this enum update as it should not be allocated by the
> >>>> +application [suppress_type]
> >>>> +	type_kind = enum
> >>>> +	name = rte_cpu_flag_t
> >>>> +	changed_enumerators = RTE_CPUFLAG_NUMFLAGS
> >>>
> >>> The justification is not correct.
> >>> The application is allowed to use RTE_CPUFLAG_NUMFLAGS in array
> >> allocation.
> >>> But no API is returning a CPU flag, so the new flags will remain
> >>> unknown to the application.
> >>>
> >>> However, there is a behaviour change:
> >>> The functions rte_cpu_get_flag_name() and
> rte_cpu_get_flag_enabled()
> >>> will now accept new values, which were previously considered as an
> error.
> >>> Is it an ABI breakage? I would say no.
> >>
> >> We saw something similar with the Cryptodev's
> >> rte_crypto_sym_xform_type also.
> >> Libabigail appears to be particularly sensitive to changes to enumerations.
> >> Leaving it to the user to decide if there is a problem.
> >>
> >> I am seeing a bit of weirdness though between versions of libabigail.
> >> 1.7.1 seems to fine with the change, however 1.2 is reporting an issue.
> >>
> >> Kevin - what version are you using?
> >
> > I'm using version 1.6.0
> 
> right you are either on Fedora 31 or some Ubuntu v19.xx, right?

At the time of making the patch: Ubuntu 18.04 with a manually upgraded libabigail
Currently Ubuntu 20.04 (beta). 

> 
> >
> >>
> >>>
> >>> PS: Who is REALLY maintaining the ABI?
> >>> We really miss someone who carefully check all these things, and
> >>> take care of the doc and tooling.
> >>>
> >>>
> >>
> >> I would say that I am missing these changes to libabigail.ignore,
> >> which would be useful.
> >> Should we consolidate the ABI Policy and ABI Versioning sections of
> >> the MAINTAINERS file?
> >