Messages in this thread |  | | From | Arnd Bergmann <> | Date | Sat, 9 Jan 2021 22:52:53 +0100 | Subject | Re: Old platforms: bring out your dead |
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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.
I checked some distros and found that aside from Debian inadvertently dropping i486 a long time ago, Slackware 14.2 (from 2016) also requires an i586 or higher now. Slackware 14.1 (from 2013) is still supported on i486 but ships with a Linux-3.10 kernel. archlinux32 is the only binary distro I could find that still officially supports i486, which in their case means anything below an i686 (cmov+mmx+sse). If it gets dropped, it might require some users to stay on LTS kernels after the distro moves to i586-only kernel, but as there are no long-term supported releases, there is also no need to coordinate the timing.
As with the other older platforms, the main question to ask is: Are there users that are better off running a future LTS kernel on this hardware than the v5.10.y version or something older?
Arnd
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