Messages in this thread | | | From | David Laight <> | Subject | RE: Old platforms: bring out your dead | Date | Mon, 11 Jan 2021 09:50:41 +0000 |
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From: Arnd Bergmann > Sent: 09 January 2021 21:53 > > On Sat, Jan 9, 2021 at 6:56 AM Willy Tarreau <w@1wt.eu> wrote: > > > > On Fri, Jan 08, 2021 at 11:55:06PM +0100, Arnd Bergmann wrote: > > > * 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 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.
David
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