linux-kernel - Re: Old platforms: bring out your dead

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Message-ID: <CAP8WD_aUn4UrfNr9ROeNQ0x=xCXfS-mceUAM=fXz1n12Smmd6A@mail.gmail.com>
Date:   Mon, 11 Jan 2021 21:05:59 -0500
From:   tedheadster <tedheadster@...il.com>
To:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:     Shuah Khan <skhan@...uxfoundation.org>,
        Krzysztof Adamski <krzysztof.adamski@...ia.com>,
        Oleksij Rempel <o.rempel@...gutronix.de>,
        Baruch Siach <baruch@...s.co.il>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Daniel Tang <dt.tangr@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Jamie Iles <jamie@...ieiles.com>,
        Barry Song <song.bao.hua@...ilicon.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Jonas Jensen <jonas.jensen@...il.com>,
        Marc Gonzalez <marc.w.gonzalez@...e.fr>,
        Hartley Sweeten <hsweeten@...ionengravers.com>,
        Lubomir Rintel <lkundrak@...sk>,
        Neil Armstrong <narmstrong@...libre.com>,
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        Hans Ulli Kroll <ulli.kroll@...glemail.com>,
        Vladimir Zapolskiy <vz@...ia.com>,
        Wei Xu <xuwei5@...ilicon.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
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        Michael Ellerman <mpe@...erman.id.au>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Subject: Re: Old platforms: bring out your dead

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