From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alex Vong <alexvong1995@gmail.com>
Subject: Re: (dynamic-link "libm") doesn't work on guile
Date: Sat, 09 Jan 2016 22:08:13 +0800
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In-Reply-To: <87vb74ji1y.fsf@gnu.org> ("Ludovic
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To: Ludovic =?utf-8?Q?Court=C3=A8s?= <ludo@gnu.org>
Cc: help-guix@gnu.org

ludo@gnu.org (Ludovic Court=C3=A8s) writes:

> Alex Vong <alexvong1995@gmail.com> skribis:
>
>> I think it is weird. It seems only dynamic linking with "libc" or "libm"
>> fails, dynamic linking with external library like "libpcre2-8" or
>> anyhome-made shared library would work. And yes, "libc-2.22" and
>> "libm-2.22" also works for me.
>
> I think that=E2=80=99s because libm.so and libc.so are linker scripts, wh=
ereas
> libm-2.22.so and libc-2.22.so are the actual ELF files:
>
> $ cat ~/.guix-profile/lib/libm.so
> /* GNU ld script
> */
> OUTPUT_FORMAT(elf64-x86-64)
> GROUP ( /gnu/store/qv7bk62c22ms9i11dhfl71hnivyc82k2-glibc-2.22/lib/libm.s=
o.6  AS_NEEDED ( /gnu/store/qv7bk62c22ms9i11dhfl71hnivyc82k2-glibc-2.22/lib=
/libmvec.so.1 ) )
> $ cat ~/.guix-profile/lib/libc.so
> /* GNU ld script
>    Use the shared library, but some functions are only in
>    the static library, so try that secondarily.  */
> OUTPUT_FORMAT(elf64-x86-64)
> GROUP ( /gnu/store/qv7bk62c22ms9i11dhfl71hnivyc82k2-glibc-2.22/lib/libc.s=
o.6 /gnu/store/qv7bk62c22ms9i11dhfl71hnivyc82k2-glibc-2.22/lib/libc_nonshar=
ed.a  AS_NEEDED ( /gnu/store/qv7bk62c22ms9i11dhfl71hnivyc82k2-glibc-2.22/li=
b/ld-linux-x86-64.so.2 ) )
>
I think you are right, libm.so is a binary file in Debian, while it is a
linker script in guix. That's why it is not working.

To understand the problem, I find this thread on the glibc mailing list
<https://sourceware.org/ml/libc-alpha/2011-07/msg00139.html>,
where the developer said ``no one is saying that dlopening the C library
is wrong, but we are saying that dlopening "libc.so" instead of
"libc.so.6" is wrong.``.

Is there way to specify an ABI version (I suppose 6 is the ABI version
since we have libm.so.6) when dlopening a shared library to avoid this
glitch?

> Ludo=E2=80=99.