Power/PowerPC RIOS/RIOS2 obsolescence

[Kevin Bowling]

On Tue, Jun 29, 2010 at 7:09 AM, David Edelsohn <dje.gcc@gmail.com> wrote:
> On Tue, Jun 29, 2010 at 1:53 AM, Kevin Bowling <kevin.bowling@kev009.com> wrote:
>> In the GCC 4.5 announcement:
>>
>> "Support for the classic POWER architecture implemented in the
>> original RIOS and RIOS2 processors of the old IBM RS/6000 product line
>> has been obsoleted in the rs6000 port. This does not affect the new
>> generation Power and PowerPC architectures."
>>
>> What needs to be done to keep this code alive?  It seems fairly light
>> weight.  I can provide remote access to AIX POWER2 hardware if needed.
>
> Why should this code be maintained?
>
> Andrew Haley's well-intentioned comments are completely off the mark.
>
> Linux does not run on POWER1 or POWER2 hardware.  Recent versions of
> AIX do not run on it.  The hardware no longer is supported by IBM.
>
> Even if GCC can build and run on such a system, support for the
> original POWER ISA complicates the rs6000 port.  While the support is
> fairly mechanical, it is large and bulky.  Because of some other
> improvements the maintainers of the rs6000 port wish to make, we plan
> to remove classic POWER support to simplify the implementation of the
> new features.
>
> If there is a user community relying on modern versions of GCC for use
> on those systems, I would reconsider.  One person saying he has access
> to an AIX POWER2 system and retaining the support seems like a cool
> idea is not a reason to devote the resources.  GCC's mission is not to
> support every system in a computer history museum.  Older versions of
> GCC created at the time of those systems still will work on those
> systems.
>
> Thanks, David


This is an unfortunate attitude many people have in free software
these days, especially big business contributors with profit-aligned
motives.  Linus weighs in on a similar dissent here:
http://lwn.net/Articles/339455/.

I'm currently working on the NetBSD port:
http://www.netbsd.org/ports/rs6000/.  I also have patches that boot
the Linux kernel.  Quite simply, this stuff is interesting to me.  I
am not a professional systems programmer.  This project has a low bar
of entry and serves a pedagogic purpose to me.  I can't compete with
professional arch maintainers that handle the lower level on modern
hardware, nor do I have a POWER7 to call my own.

Finally, the CPU is used in a variety of embedded applications.  There
are over 200 RSC(POWER1) RAD6000 in space [1], including a launch in
Feb 2010.  While compiler choice in this application is almost
certainly static, GCC support provides interesting options for these
folks since you can't beam up a Core i7 just because it's fashionable.

Regards,
Kevin Bowling

[1] http://en.wikipedia.org/wiki/IBM_RAD6000