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@xxxxxxxx
