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From: Florian Weimer <fw@deneb.enyo.de>
To: Lukasz Majewski <lukma@denx.de>
Cc: libc-help@sourceware.org,  Joseph Myers <joseph@codesourcery.com>
Subject: Re: Question regarding __clock_gettime symbol visibility across glibc
 build
References: <20200317084724.6df11fb1@jawa>
Date: Tue, 17 Mar 2020 09:34:23 +0100
In-Reply-To: <20200317084724.6df11fb1@jawa> (Lukasz Majewski's message of
 "Tue, 17 Mar 2020 08:47:24 +0100")
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* Lukasz Majewski:

> However, I've checked how it looks on the installed glibc:
> root@y2038arm:/opt# nm /opt/lib/libc.so.6 | grep clock_gettime
>
> 000702bc t __GI___clock_gettime
> 00070264 t __GI___clock_gettime64
> 000702bc T __clock_gettime
> 00070264 T __clock_gettime64
> 000702bc t __clock_gettime_2
> 000702bc T clock_gettime@@GLIBC_2.17
> 000702bc T clock_gettime@GLIBC_2.4
>
> In the installed glibc the __clock_gettime64 is an external symbol.

All exported glibc symbols are versioned.  Chances are that nm does
not look at the dynamic symbol table at all, so its output is
misleading.  I usually use eu-readelf --symbols=.dynsym instead.