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Date: Thu, 07 Aug 2014 09:14:00 -0000
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Subject: =?UTF-8?B?UmU6IHVuZGVmaW5lZCBzeW1ib2w6IF9fYXRvbWljX3N0b3JlIO+8nw==?=
From: Jonathan Wakely <jwakely.gcc@gmail.com>
To: =?UTF-8?B?57qq5piO?= <jiming@yafco.com>
Cc: gcc-help <gcc-help@gcc.gnu.org>
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On 7 August 2014 10:10, =E7=BA=AA=E6=98=8E wrote:
> Hi all=EF=BC=8C
>
> I have gcc 4.9.0 installed in my system. When I tried to run an
> executable, I got the following error:
>
> libMyLib.so: undefined symbol: __atomic_store
>
> Then I tried to find this symbol in libstdc++.so with the following comma=
nd:
>
> [workspace]$ nm -DC /usr/lib64/libstdc++.so | grep atomic
> 000000348e07bdb0 T __gnu_cxx::__atomic_add(int volatile*, int)
> 000000348e05c0c0 T
> std::__atomic0::atomic_flag::test_and_set(std::memory_order)
> 000000348e05c120 T std::__atomic0::atomic_flag::clear(std::memory_order)
> 000000348e05c0c0 T
> std::__atomic0::atomic_flag::test_and_set(std::memory_order) volatile
> 000000348e05c120 T std::__atomic0::atomic_flag::clear(std::memory_order)
> volatile
> 000000348e05c1b0 T __atomic_flag_for_address
> 000000348e05c180 T __atomic_flag_wait_explicit
> 000000348e05c170 T atomic_flag_clear_explicit
> 000000348e05c160 T atomic_flag_test_and_set_explicit
>
>
> There is no __atomic_store indeed. Did I miss some flags when installing
> gcc?

You didn't say what flags you used when installing it - or even what
platform you installed it on - are we supposed to guess?

This usually means you are on a target without atomic operations, so
you need to link to GCC's libatomic.so support library.