Re: AIX support

On 19.04.24 13:04, Sriram RK wrote:
> For any complier/hardware related issue we should able to provide support.
>
> We are in the process of identifying the AIX systems that can be added
> to the CI/buildfarm environment.

I think we should manage expectations here, if there is any hope of
getting AIX support back into PG17.

I have some sympathy for this. The discussion about removing AIX
support had a very short turnaround and happened in an unrelated thread,
without any sort of public announcement or consultation. So this report
of "hey, we were still using that" is timely and fair.

But the underlying issue that led to the removal (something to do with
direct I/O support and alignment) would still need to be addressed. And
this probably wouldn't just need some infrastructure support; it would
require contributions from someone who actively knows how to develop on
this platform. Now, direct I/O is currently sort of an experimental
feature, so disabling it on AIX, as was initially suggested in that
discussion, might be okay for now, but the issue will come up again.

Even if this new buildfarm support is forthcoming, there has to be some
sort of deadline in any resurrection attempts for PG17. The first beta
date has been set for 23 May. If we are making the reinstatement of AIX
support contingent on new buildfarm support, those machines need to be
available, at least initially, at least for backbranches, like in a
week. Which seems tight.

I can see several ways going forward:

1. We revert the removal of AIX support and carry on with the status quo
ante. (The removal of AIX is a regression; it is timely and in scope
now to revert the change.)

2. Like (1), but we consider that notice has been given, and we will
remove it early in PG18 (like August) unless the situation improves.

3. We leave it out of PG17 and consider a new AIX port for PG18 on its
own merits.

Note that such a "new" port would probably require quite a bit of
development and research work, to clean up all the cruft that had
accumulated over the years in the old port. Another looming issue is
that the meson build system only supported AIX with gcc before the
removal. I don't know what it would take to expand that to support
xclang, but if it requires meson upstream work, you have that to do, too.