linux-kernel - Re: [PATCH] x86: Remove a.out support

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Message-ID: <YeHKYXssmfX9Lfrr@zn.tnic>
Date:   Fri, 14 Jan 2022 20:09:21 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Theodore Ts'o <tytso@....edu>
Cc:     X86 ML <x86@...nel.org>, Arnd Bergmann <arnd@...db.de>,
        Eric Biederman <ebiederm@...ssion.com>,
        Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: Remove a.out support

Just to answer the "do we still wanna support running original a.out
binaries" aspect...

On Thu, Jan 13, 2022 at 11:06:03PM -0500, Theodore Ts'o wrote:
> > > Let's pour one out for being able to run Minix binaries on Linux.  :-)
> > 
> > https://en.wikipedia.org/wiki/Minix_3:
> > 
> > "2013-02-21 ... Dropped support for a.out binaries"
> > 
> > They themselves killed that support a lot earlier. :-)
> 
> Well, Minix 3 is a very different beast than the Minix 1.x

Right, but if the Minix 1.x successor has deemed a.out support obsolete
and has removed in 2013 I figure we can too. :-)

And, btw, Alan had a good, practical idea at the time we talked about
deprecating a.out support:

https://lore.kernel.org/all/20190305134347.4be2449c@alans-desktop/

And that is probably the best thing to do: if people wanna run old a.out
binaries, they can either write an a.out loader as an ELF program or
slap an old linux distro in a VM and do that there just fine.

If you look at the original thread which started this:

https://lore.kernel.org/all/CAG48ez1RVd5mQ_Pb6eygQESaZhpQz765OAZYSoPE0kPqfZEXQg@mail.gmail.com/

it looked even back then like a.out support is so rusty, bitrotten and
broken that we're probably even doing ourselves a favor to remove it.

Especially if not even the toolchains would even create an a.out
executable and no one even noticed.

So...

> that Linus used when he was boot-strapping Linux back in 1991. :-)
>
> Among other things Minux 1.x is system call compatible with the
> original V7 Unix from AT&T, whereas Minux 2.x and higher switch to
> having system calls that were Posix comaptible --- and Minix 2, being
> at teaching OS, wouldn't have kept any backwards compatibility when
> Prof. Tannenbaum released the 2nd edition of his Operating Systems
> Design and Implementation book in 1997.

I had a lot of fun reading that book. :-)

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette