Linux Kernel Drops Support For Old Intel 386 CPUs

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Originally Posted by Pallidus

are there real world examples of people really compiling the latest kernel releases and using them on 486's?

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I know there are many embedded controllers that are basically cloned i486 chips. I'm of the mind that they'd be better served running kernel 2.2 or 2.4 with an old revision of the toolchain, though.

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Originally Posted by Pallidus

wouldn't it be better to drop anything prior to pentium4's??

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Well this is where it gets tricky. After the i386, there's not much to be gained by dropping things until you get up to the i686, which encompasses the PentiumPro, Pentium II, Pentium III, Pentium-M, and Core (not 'Core 2'). Dropping 'up to the Pentium 4' would actually kill-off a LOT of totally viable not-so-old chips, like the first Intel MacBooks!

Were I the King of Linux, glibc, and GCC, I would push to drop up to (but not including) the PentiumPro architecture (i686), dropping the 486, 586, and some VIA Cyrix/C3 CPUs that need special treatment along the way. Let those old chips get served by older releases, while the 32-bit x86 architecture is kept to only the PentiumPro and the Netburst (Pentium 4) cores.

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Originally Posted by Hamish Wilson

Might be a bit too close a shave. I am still running Linux quite well on an old AthlonXP.

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You'd want to keep at least the Pentium 3 / Athlon tbird generation working. I think an argument could be made that Pentium 2's are getting pretty darn old.

Edit: and as mentioned above, if you support the P3 it means you might as well just support back to the original i686 architecture.

I still have a few p2 that i do some testing on from time to time :)

So does anyone know anybody who actually still uses 80386? Anybody? Anyone at all?

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Originally Posted by oliver

So does anyone know anybody who actually still uses 80386? Anybody? Anyone at all?

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I think that's the same thing the kernel folks asked, and the answer was 'no'. Between that and the advantages of not needing to program around that processor's limitations, it made sense to remove it.

You have to remember that Linux support doesn't center on the desktop, it spans from giant NUMA systems to tiny embedded controllers on appliances. Here's an example of a recently-sold board that DOES use an honest-to-goodness i386:

http://www.dmp.com.tw/tech/m6117d/

Realistically, it's probably about time for some policies about hardware support to start being made. It might make sense to deprecate older hardware options right after 'long-term support' kernels are spawned.

I can't believe that some of you would want to drop support for 586 class CPUs. There are still some good uses for older machines, such as a router/firewall/low volume email server. I am still using an old PowerMac G3 as a server for active port forwarder and ssh tunneling. Also, there may very well be some 586 and 486 class machines still in use for login/password authentication or running ATMs. Drop support for these machines and we could have a small data security pandemic.

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Originally Posted by schmidtbag

the thing about ditching other ancient archs that may still be in use (such as i486) is the modern kernel is likely too heavy for them, nearly none of the new features put into the kernel will actually aid old archs, and people who use them probably don't care to update to the latest anyway.

While it is a little sad that the original arch is being ditched, I'm glad to see the kernel getting cleaned up a bit and making future releases easier to work on.

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Improvements to hardware independent things like filesystems, network protocols, scheduling, etcetera would still benefit older architectures.

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but not to an i386. It will be to slow to do most if anything really.

486 is quite a different beast though imo and actually is used more commonly (though 586 even more so) in the embedded x86 world.

As for your G3 ... I'm pretty sure you can safe yourself quite some money, bye investing in some cheap arm based router or the like (mele a1000 even) and safe a boatload on electricity. Just because old technology can and does work, doesn't make it the smartest choice straight away. I know, I speak from experience. While it is extremely cool having some old box humming about still performing work, it simply can cost way more then its worth due to the higher energy bill generated from it.

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Originally Posted by oliver

Two the two above posts:

but not to an i386. It will be to slow to do most if anything really.

486 is quite a different beast though imo and actually is used more commonly (though 586 even more so) in the embedded x86 world.

As for your G3 ... I'm pretty sure you can safe yourself quite some money, bye investing in some cheap arm based router or the like (mele a1000 even) and safe a boatload on electricity. Just because old technology can and does work, doesn't make it the smartest choice straight away. I know, I speak from experience. While it is extremely cool having some old box humming about still performing work, it simply can cost way more then its worth due to the higher energy bill generated from it.

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Any architecture should benefit from the algorithmic improvements and bug fixes.

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Originally Posted by alpha_one_x86

Linux kernel + small env need 4MB of memory minimum. But this config is mostly under P1 minimum, then drop the 486 can be a good idea. But if not add amount of code and emulation... If the support is same as P4, ... why don't keep it.
I'm to keep the old compatilibity if newer than 10 years old (else you have older linux -> kernel + OS, or emulation) or if don't block the evolution.

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386 memory access was different
instruction set not so much

everything above till amd64 is almost the same