O'pain Software Foundation: (2) Why is it better than AT&T?

[Guy Harris]

> My current impression (admittedly somewhat uninformed) is that the ABI
> standard (I assume this is what John is referring to) is a crock.  Given
> the recent explosion of micro-processor designs which have come out in the
> last year, the notion of an ABI seems to me to be useless.

Maybe, maybe not.  If you expect every box out there to have its own
architecture, yes.  If you expect some number of architectures to be dominant,
so that there are a large number of boxes with a particular architecture (68K,
80*86, MIPS, SPARC, whatever), probably not - if the ability to package one
version of a particular piece of software (or, at least, one per distribution
medium) and have it run on *all* boxes using members of a particular processor
family causes lots more of this software to be available at reasonable prices,
an ABI for that processor family is far from useless.

Note that the phrase "*the* ABI standard" has no unique referent; the SPARC ABI
is just one of many ABIs - AT&T presumably intends to support both the '386 and
SPARC ABIs, as they currently have a '386 machine and will have SPARC machines,
and Sun will probably end up supporting those and quite possibly a 68K ABI as
well.  (Note: I obviously don't speak for AT&T here, and can't speak for Sun
either; I don't make those decisions.)

> The current System V release is based upon the 3b2 architecture.  My
> understanding is that future releases will be based upon the SPARC
> architecture.  In this sense,  no effort has been made by AT&T/Sun to
> "make it possible to run the same applications software on hundreds of
> manufacturer's machines."

AT&T has *never* made such an effort, in the sense that they have never shipped
UNIXes for every architecture in existence.  They have promoted the
"microports" of S5 to various chip families; I think the ports themselves were
done outside AT&T.

I would *personally* like to see the source release of UNIX provide support for
some non-singleton set of processors - Sun builds its Sun-2/Sun-3 and Sun-4
versions from common source, and builds most of its Sun386i version from that
source as well - but the problem here is "which processors get on the tape?"
'386?  SPARC?  AT&T currently makes a '386 machine (or, at least, sells one; I
don't know if they, Olivetti, or somebody else makes it), and eventually plans
to make a SPARC machine.  68K?  While Sun may make 68K machines, AT&T currently
doesn't.  MIPS?  AT&T doesn't make a MIPS machine.  VAX?  Clipper?  Cray-2?
etc., etc., etc..