[Openmcl-devel] OpenMCL right choice for PPC Linux?

[Gary Byers]

On Sun, 28 Aug 2005, Derrick Baumer wrote:

> Hello.  I am enjoying using OpenMCL 0.14.3 on my 330 Mhz iMac
> running Ubuntu Linux (who do I mail the check to?) ;)
>

That's the attitude that we like to see.

> I read with interest recently about Apple switching to Intel
> hardware but never saw the conclusion to the thread.  Would
> the OpenMCL developers continue to develop this product for
> the PPC architecture when/if that happens?

Yes (or at least "Yes, as far as I can see.")

Linux (and LinuxPPC) have been changing in the last few years; the
underlying ABI has changed a bit to support thread-local-storage (TLS)
and the New POSIX Threads Library (NPTL.)  Different Linux
distributions have offered different levels of support for these
features; if Debian (on which Ubuntu is based) supports them, I think
that that's a relatively recent development.  Some other distributions
(YDL 4.x, Fedora Core, Gentoo, IIRC) have been more aggressive about
this.

OpenMCL violates the TLS-related ABI changes (it uses the r2 register
for its own evil purposes), and released versions of OpenMCL may not
run (or run reliably) on Linux platforms that are to some degree
TLS-based.  (Exactly what works and what doesn't depends on how fully
TLS is used in the distribution.)

One of the goals of the next release is to fix this (OpenMCL will keep
its hands off of r2.)  Sometime (hopefully soon) after the next
release, a LinuxPPC64 version should be available.

>
> Also, most of the traffic I've seen has been OS-X-centric.
> I'm concerned about the possibility of support of PPC Linux
> being dropped - is that possible?

I think that the ABI breakage may have caused some Linux OpenMCL users
to have drifted away.  (I think that Linux users have always been in
the minority, but I suspect that some people may have reported
problems that I couldn't reproduce and/or didn't understand, and may
have gotten frustrated.)

For what it's worth, I have more machines running PPC Linux here than
I have running OSX (and the next OpenMCL release should run reliably
on all of them.)  I personally find Linux to be better designed and
better implemented than Darwin (the parts of OSX that're attractive
and usable are probably the parts that're as far away from Mach as
they can get ...).  My preference doesn't have much to do (either way)
with whether it makes business sense for Clozure to continue to
support PPC Linux, but I think that I'd do some kicking and screaming
if we were ever to decide not to.

>
> Basically, I'm working on a long-term project and I would
> like to know that my development environment will continue to
> work with my OS/hardware, and I'm asking if I should stick
> with OpenMCL or look for something else.

I wish that I could say that "absolutely, positively, OpenMCL
will be well supported on PPC (including LinuxPPC) for the long-term
foreseeable future."  (I can say that that's Clozure's intent, and
I don't think that Apple's announcement has -too- much to do with
that.)  If Clozure's a viable company for the foreseeable future -
and I certainly hope that we are - then I can't see any reason
why we'd stop supporting the PPC; I can't see the platform becoming
so hard to maintain/uninteresting/irrelevant that we'd be forced
to drop it.

(We -are- working on this whole "getting and staying viable" thing.)

>
> Thank you,
> Derrick Baumer