On Mon, Jan 11, 2021 at 11:55 AM David Laight [off-list ref] wrote:

From: Arnd Bergmann

quoted

Sent: 09 January 2021 21:53

On Sat, Jan 9, 2021 at 6:56 AM Willy Tarreau [off-list ref] wrote:

quoted

On Fri, Jan 08, 2021 at 11:55:06PM +0100, Arnd Bergmann wrote:

quoted

* 80486SX/DX: 80386 CPUs were dropped in 2012, and there are
  indications that 486 have no users either on recent kernels.
  There is still the Vortex86 family of SoCs, and the oldest of those were
  486SX-class, but all the modern ones are 586-class.

These also are the last generation of fanless x86 boards with 100% compatible
controllers, that some people have probably kept around because these don't
age much and have plenty of connectivity. I've used an old one a few times
to plug in an old floppy drive, ISA SCSI controllers to access an old tape
drive and a few such things. That doesn't mean that it's a good justification
not to remove them, what I rather mean is that *if* there is no benefit
in dropping them maybe we can keep them. On the other hand, good luck for
running a modern OS on these, when 16MB-32MB RAM was about the maximum that
was commonly found by then (though if people kept them around that's probably
because they were well equipped, like that 64MB 386DX I'm having :-)).

I think there were 486s with up to 256MB, which would still qualify as barely
usable for a minimal desktop, or as comfortable for a deeply embedded
system. The main limit was apparently the cacheable RAM, which is limited
by the amount of L2 cache -- you needed a rare 1MB of external L2-cache to
have 256MB of cached RAM, while more common 256KB of cache would
be good for 64MB. Vortex86SX has no FPU or L2 cache at all, but supports
256MB of DDR2.

There are also some newer (well less than 30 year old) cpus that are

(less than 10 years actually)

basically 486 but have a few extra instructions - probably just cpuid
and (IIRC) rdtsc.
Designed for low power embedded use they won't ever have been suitable
for a desktop - but are probably fast enough for some uses.
I'm not sure how much keeping 486 support actually costs, 386 was a
PITA - but the 486 fixed most of those issues.

Right, we have "last of mohicans" (to date) Intel Quark family of CPUs
(486 core + few i586 features).
This is for the embedded world and probably not for powerful use.

-- 
With Best Regards,
Andy Shevchenko

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