Re: AIX support

On Fri, Apr 19, 2024 at 6:01 AM Andres Freund <andres@anarazel.de> wrote:
> On 2024-04-18 11:15:43 +0000, Sriram RK wrote:
> > We (IBM-AIX team) looked into this issue
> >
> > https://www.postgresql.org/message-id/20240225194322.a5@rfd.leadboat.com
> >
> > This is related to the compiler issue. The compilers xlc(13.1) and gcc(8.0)
> > have issues. But we verified that this issue is resolved with the newer
> > compiler versions openXL(xlc17.1) and gcc(12.0) onwards.
>
> The reason we used these compilers was that those were the only ones we had
> kinda somewhat reasonable access to, via the gcc projects'
> "compile farm" https://portal.cfarm.net/
> We have to rely on whatever the aix machines there provide. They're not
> particularly plentiful resource-wise either.

To be fair, those OSUOSL machines are donated by IBM:

https://osuosl.org/services/powerdev/

It's just that they seem to be mostly focused on supporting Linux on
POWER, with only a couple of AIX hosts (partitions/virtual machines?)
made available via portal.cfarm.net, and they only very recently added
a modern AIX 7.3 host. That's cfarm119, upgraded in September-ish,
long after many threads on this list that between-the-lines threatened
to drop support.

> This is generally one of the big issues with AIX support. There are other
> niche-y OSs that don't have a lot of users, e.g. openbsd, but in contrast to
> AIX I can just start an openbsd VM within a few minutes and iron out whatever
> portability issue I'm dealing with.

Yeah.  It is a known secret that you can run AIX inside Qemu/kvm (it
appears that IBM has made changes to it to make that possible, because
earlier AIX versions didn't like Qemu's POWER emulation or
virtualisation, there are blog posts about it), but IBM doesn't
actually make the images available to non-POWER-hardware owners (you
need a serial number).  If I were an OS vendor and wanted developers
to target my OS for free, at the very top of my TODO list I would
have: provide an easy to use image for developers to be able to spin
something up in minutes and possibly even use in CI systems.  That's
the reason I can fix any minor portability issue on Linux, illumos,
*BSD quickly and Windows with only moderate extra pain.  Even Oracle
knows this, see Solaris CBE.

> > We want to make a note that postgres is used extensively in our IBM product
> > and is being exploited by multiple customers.
>
> To be blunt: Then it'd have been nice to see some investment in that before
> now. Both on the code level and the infrastructure level (i.e. access to
> machines etc).

In the AIX space generally, there were even clues that funding had
been completely cut even for packaging PostgreSQL.  I was aware of two
packaging projects (not sure how they were related):

1.  The ATOS packaging group, who used to show up on our mailing lists
and discuss code changes, which announced it was shutting down:

https://github.com/power-devops/bullfreeware

2.  And last time I looked a few months back, the IBM AIX Toolbox
packaging project only had PostgreSQL 10 or 11 packages, already out
of support by us, meaning that their maintainer had given up, too:

https://www.ibm.com/support/pages/aix-toolbox-open-source-software-downloads-alpha

However I see that recently (last month?) someone has added PostgreSQL
15, so something has only just reawoken there?

There are quite a lot of threads about AIX problems, but they are
almost all just us non-AIX-users trying to unbreak stupid stuff on the
build farm, which at some points began to seem distinctly quixotic:
chivalric hackers valiantly trying to keep the entire Unix family tree
working even though we don't remember why and th versions involved are
out of support even by the vendor.  Of the three old giant commercial
Unixes, HP-UX was dropped without another mention (it really was a
windmill after all), Solaris is somehow easier to deal with (I could
guess it's because it influenced Linux and BSD so much, ELF and linker
details spring to mind), while AIX fails on every dimension:
unrepresented by users, lacking in build farm, unavailable to
non-customers, and unusual among Unixen.