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Subject: Re: Old platforms: bring out your dead
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Arnd,

> * 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.

I actively use the i486DX systems for regression testing and they have
proven useful for detecting bugs in both the kernel and GCC (see
below).

I am also about to use them as testing systems for kernel programming
students. I would hate to lose this platform as a student learning
opportunity.

Here are just some of the patches that I have worked on myself:

Kernel patches i486 testing uncovered:

x86/boot: Fix another __read_cr4() case on 486
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=192d1dccbfc5b901b66527df9df80304693cf06e

x86/CPU: Change query logic so CPUID is enabled before testing
https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=2893cc8ff892fa74972d8dc0e1d0dc65116daaa3

GCC patches i486 contributed to:

ibgcc calls __get_cpuid with 0 level breaks on early 486
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=a6c78ea30381cc28ea0b2cf8f0bd584a91dda948

ICE in gen_lowpart_general, at rtlhooks.c:63
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=980c8afc0961da4b4567a5abe85b6048d501a1ad

So, these systems are _quietly_ being used, and helping to contribute,
it's just not glamorous, eye-catching work.

- Matthew Whitehead