P2 CPU "class," but 386/486 ISA "core" are commonplace -- WAS: i586/686 glibc/kernel

[Bryan J. Smith]

This isn't about making a "lite" distro.
Fedora "Core" _should_ continue to ship with the _same_ performance,
memory and storage requirements.

I'm talking about not assuming that a 100MHz+ system has a Pentium ISA
(instruction set architecture) compatible CPU or higher.  Most people
seem to assume this, when there are a _lot_ of systems that don't.
A _lot_ of 100MHz+ CPUs.

We're talking a "system-on-a-chip" that eats up maybe 1-2Ws, or maybe
hundreds of milliwatts.  But they run at 133MHz or even higher, have
32-bit or even 64-bit memory bus interfaces, support even 128Mbit SDRAM
technology (upto 512MB of SDRAM) and have peripherials up the wazzu on
the chip itself (PCI masters, ATA100, PCCard/PCMCIA, USB, etc...).

But the ISA is often only a 486 or lower!  Even when the product is sold
as 5th-Gen (Pentium) or 6th-Gen (Pentium II) "class" chip!

Now AMD has licensed National Semi's Geode products.  The Geode are the
Cyrix M2 core, which are Pentium ISA.  These are quickly commonplace.

But AMD was is still selling its E86/SCLAN series too (and was its
_only_ product for awhile), which kicks some serious butt at 133MHz,
with lots of on-board peripherials.

Same deal with STMicro and others.  These are _huge_ in Europe, as well
as non-US markets, and a lot of imports into the US as well.  STMicro is
notorious for marketing them as "Pentium/Pentium-II" class because they
run at 100MHz, have 64-bit memory busses, PCI, ATA, USB, etc...
support.  But underneath, the _majority_ of STMicro products are i486
ISA.

These systems are all over the place.  In black boxes atop of your TV
that have 128MB+ of RAM, 10-20GB disks, etc...  Serious power.

That's why I'm all for making the distro i686 optimized, but i386 ISA
compatible.  With x86-64 being adopting this year, there is little
reason to start worrying about "performance."  x86-64 distros will be
optimized to the max, because x86-64 is a whole new architecture.

But for plain Jane x86, there is little sense to break i386 ISA
compatibility.  Yes, _assume_ the "performance/memory/disk" equivalent
of a Pentium Pro/II or higher.  But leave the instruction set
compatibility (ISA) at i386 -- please, for Fedora adoption sake.


-- 
Bryan J. Smith, E.I. -- b.j.smith at ieee.org