Leonard den Ottolander wrote:
This issue was discussed in the thread "Making NPTL the default
for
FC3, vanilla i386 support". Both i386s and i486s are already no longer
supported since FC 1. Try running rpm on either of these CPUs and see
it fail. See
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=103078 .
FYI, the original Cyrix 686 (M1?) was only i486 compatible. You had to go
with the 686"L" or M2 to get full i586 ISA compatibility.
Frankly, I don't think people recognize the _real_ reason for trying to
keep i386/486 ISA compatibility. It's not to support old systems, but to
support i386/486 ISA embedded microprocessor cores in all sorts of black
box solutions. These solutions have full desktops/GUIs far more than you
may think.
All it takes is one major black box vendors to adopt Fedora and we're
talking over a 1% marketshare.
GCC still pumps out i386 ISA code, while making other optimizations. So
anything that has a patch or otherwise that breaks this should be
revisited. So there is still a good reason to strive for i386/486 ISA.
So if there is the intention of making the move to i486 as the
minimum
arch we could just as well make the jump to i586.
I would continue to favor i386 with i686 (Pentium Pro) optimizations.
i586 (Pentium) causes a lot of de-optimizations in newer processors, even
Intel's own. Why? Understand that about 80% of "Pentium optimizations"
were really "errata workarounds." The Pentium was the first superscalar
x86 design, and boy did it have some real muck-ups that had to be
compensated in software (like the ALU LOAD being 3x slower, which id
found it far faster to load via integers via the FPU instead).
--
Bryan J. Smith, E.I. -- b.j.smith(a)ieee.org