linux-kernel - Re: [PATCH 0/5] remove the last bits of a.out support

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Message-ID: <877cm6tpvq.fsf@email.froward.int.ebiederm.org>
Date:   Fri, 24 Nov 2023 22:31:53 -0600
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     Dimitri John Ledkov <dimitri.ledkov@...onical.com>
Cc:     Richard Henderson <richard.henderson@...aro.org>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        Matt Turner <mattst88@...il.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H . Peter Anvin" <hpa@...or.com>, linux-alpha@...r.kernel.org,
        linux-m68k@...ts.linux-m68k.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/5] remove the last bits of a.out support

Dimitri John Ledkov <dimitri.ledkov@...onical.com> writes:

> On Fri, 24 Nov 2023 at 14:36, Dimitri John Ledkov
> <dimitri.ledkov@...onical.com> wrote:
>>
>> On Fri, 24 Nov 2023 at 06:01, Eric W. Biederman <ebiederm@...ssion.com> wrote:
>> >
>> > Dimitri John Ledkov <dimitri.ledkov@...onical.com> writes:
>> >
>> > > I was working on how linux-libc-dev headers are shipped in Ubuntu and
>> > > stumbled upon seemingly unused and useless linux/a.out.h header. It
>> > > seems like it is an accidental leftover at this point.
>> >
>> > How do you see that they are unused?
>
> When I did my code search the only and last remaining userspace code
> that imports linux/a.out.h it is the objtool that is patched in these
> patch series.
> It is also vendored as copy in aboot tool, which has been patched in
> many downstreams to use a.out.h instead of linux/a.out.h.

It sounds like you have done your homework.

Please just document (as you in your reply to me) in your cover letter
or elsewhere in the changes so that it is clear that due diligence has
been performed and userspace should not break with this change.

[snip]

> Was your search
> https://codesearch.debian.net/search?q=linux%2Fa.out.h&literal=1&perpkg=1
> ?

Pretty much.  I didn't have the perpkg=1.

Debian code search is the most comprehensive code search I am aware
of so I took a quick look.

Since it appears the only users are vendored versions of linux/a.out.h
then it should be possible to make this change without breaking
userspace.  If it turns that is wrong the changes can be reverted.

Eric