Re: [dpdk-dev] [PATCH] eal:ppc: fix incorrect ifdef for ppc_64

[David Marchand <david.marchand@redhat.com>]

On Thu, Oct 17, 2019 at 6:56 PM David Christensen
<drc@linux.vnet.ibm.com> wrote:
>
> >>>> The change itself is not that scary, but just reading this commitlog I
> >>>> fail to see the impact for an application.
> >>>> Can you share some light?
> >>>>
> >>>
> >>> As far as I can tell there is no impact on any applications.  The old
> >>> code, which walked through the list in a forward direction, worked
> >>> perfectly well with testpmd and DPDK pktgen applications on Power systems.
> >>>
> >>> With the ifdef fixed, the core walks the list in the reverse direction
> >>> as intended, the code still worked (i.e. no errors or problems were
> >>> observed in the same test applications).
> >>>
> >>> I'm not completely familiar with why memseg lists must be traversed in
> >>> the reverse direction for Power systems.  It might be something specific
> >>> to Power 8 systems which I'm not actually supporting on DPDK, only the
> >>> Power 9 systems that I use for for development and testing.
> >>>
> >> If the code makes no difference anyway, should we just take it out so?
> >
> > +1 :-)
>
> I think there's a need for a larger review of Power8 vs. Power9 support.
>   You currently need to specify Power8 as the DPDK build target (e.g.
> ppc_64-power8-linux-gcc) but all of our internal development and testing
> efforts are targeting Power9 systems.  My preference would be to drop
> Power8 support all together but I'm reluctant to make such a potentially
> large change so close to an LTS release target, and not without
> soliciting some community comment on the idea.  As a result, I'd prefer
> to keep the change "as is" for this release.

Ok, I will take it as is, but please do investigate this.
The lesser special cases like these, the better.


-- 
David Marchand