Re: [dpdk-dev] [PATCH] ppc64: fix compilation of when AltiVec is enabled

[Thomas Monjalon <thomas@monjalon.net>]

05/11/2018 22:20, Pradeep Satyanarayana:
> From: Thomas Monjalon <thomas@monjalon.net>
> > 30/08/2018 13:58, Christian Ehrhardt:
> > > On Thu, Aug 30, 2018 Takeshi T Yoshimura <TYOS@jp.ibm.com> wrote:
> > > > Hi,
> > > > I could reproduce the issue you reported in 18.08 with my ppc64le
> > > > box with RedHat 7.5 and GCC4.8.
> > > > The patch resolved the issue in my environment. Thanks!
> > >
> > > I added your test (tanks) and Adrien's extensive review/discussion as
> > > tags and also addressed a few checkpatch findings.
> > > V2 is up on the list now ...
> > >
> > > > I am a bit newbie in dpdk-dev, but I will try contacting Chao
> > > > and other IBM guys... Sorry for our slow reply.
> > >
> > > Thanks for your participation Takeshi,
> > > we at least now have had a few replies after Thomas used the
> > > superpowers of "CPT. CAPSLOCK" \o/.
> > >
> > > I also have a call later today to make sure this is brought up
> > > inside IBM to make sure someone is maintaining it for real.
> >
> > Summary of the situation:
> >    - I used caps lock on August 30th
> >    - We got replies on the ML in the next 2 days (Alfredo, Chao, Takeshi)
> >    - On September 3rd, Adrien raised a major issue for C++ with the fix v3
> > 		http://mails.dpdk.org/archives/dev/2018-September/110733.html
> >    - Another email about a possible GCC fix on September 5th (David Wilder)
> 
> As Dave mentioned that is only expected in GCC 9.
> 
> >    - There was a private reply on September 27th, confirming an IBM support
> >    - and nothing else
> >
> > Nobody at IBM requests to get a compilation fix for ppc64.
> 
> Yes, we do need fixes for ppc64.
> 
> (1) http://mails.dpdk.org/archives/dev/2018-August/110499.html
> (2) http://mails.dpdk.org/archives/dev/2018-September/110961.html
> 
> Based on the above 2 URLs (tested both by Takeshi and David Wiler), we
> assumed that it would get picked up in 18.11.
> We have been more focussed on 17.11 (and likely dropped
> the ball on 18.11)
> since 17.11 is an LTS release and we have had lots of problems on ppc64.

Note that 18.11 is also LTS.

> Should be submitting patch to fix those issues shortly.

Sorry, I have some doubts for two reasons:
	- track records
	- technical reality: there is no perfect solution outside of GCC

> We have built 18.11-rc1 with the fix above (1), and it does work on
> ppc64le.

But it would break C++ applications.

> An updated version of:
> 
> (3) http://mails.dpdk.org/archives/dev/2018-August/109926.html
> 
> also builds on ppc64.  The latter has the advantage of possibly not
> breaking existing applications.

But it fixes only mlx5.
stdbool is used in many other places.
Which PMDs are you compiling?
Are you compiling examples?

> > And there was no issue raised after 18.11-rc1 release.
> > I guess it means DPDK is not used on ppc64.
> > In this case, we should mark the ppc port as unmaintained for 18.11.
> >
> > OR SHOULD I USE MY CAPS LOCK AGAIN?
> 
> Thanks for your patience while we iron out the issues.
> Hopefully, we don't need the CAPS LOCK again.

We have to mention the ppc64 incompatibility in 18.11 release notes.
Either it stays as is and we declare DPDK 18.11 not supported on
IBM platforms, or we fix it and document the limitations.