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From:   Florian Weimer <fweimer@redhat.com>
To:     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc:     carlos <carlos@redhat.com>, Joseph Myers <joseph@codesourcery.com>,
        Szabolcs Nagy <szabolcs.nagy@arm.com>,
        libc-alpha <libc-alpha@sourceware.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ben Maurer <bmaurer@fb.com>,
        Peter Zijlstra <peterz@infradead.org>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        Will Deacon <will.deacon@arm.com>,
        Dave Watson <davejwatson@fb.com>, Paul Turner <pjt@google.com>,
        Rich Felker <dalias@libc.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-api <linux-api@vger.kernel.org>
Subject: Re: [PATCH 1/5] glibc: Perform rseq(2) registration at C startup and thread creation (v10)
References: <20190503184219.19266-1-mathieu.desnoyers@efficios.com>
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Date:   Fri, 14 Jun 2019 13:35:51 +0200
In-Reply-To: <1635690189.3049.1560507249693.JavaMail.zimbra@efficios.com>
        (Mathieu Desnoyers's message of "Fri, 14 Jun 2019 06:14:09 -0400
        (EDT)")
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* Mathieu Desnoyers:

> * Makefile:
>
> LIBCPATH=/home/efficios/glibc-test/lib
> KERNEL_HEADERS=/home/efficios/git/linux-percpu-dev/usr/include
> CFLAGS=-I${KERNEL_HEADERS} -L${LIBCPATH} -Wl,--rpath=${LIBCPATH} -Wl,--dynamic-linker=${LIBCPATH}/ld-linux-x86-64.so.2
>
> all:
> 	gcc ${CFLAGS} -o a a.c
> 	gcc ${CFLAGS} -shared -fPIC -o s.so s.c

For me, that does not correctly link against the built libc because the
system dynamic loader seeps into the link.

> specifically this commit:
> https://github.com/compudj/glibc-dev/commit/c49a286497d065a7fc00aafd846e6edce14f97fc

This commit links __rseq_handled into libc.so.6 via rseq-sym.c, but does
not export it from there.

Thanks,
Florian