Valgrind 'noise'，这是什么意思？

Question

当我使用valgrind帮助调试我正在开发的应用程序时，我注意到一片嘈杂声，似乎是在抱怨标准库。作为测试，我这样做了；

echo 'int main() {return 0;}' | gcc -x c -o test -

然后我做了这件事

valgrind ./test

==1096== Use of uninitialised value of size 8
==1096==    at 0x400A202: _dl_new_object (in /lib64/ld-2.10.1.so)
==1096==    by 0x400607F: _dl_map_object_from_fd (in /lib64/ld-2.10.1.so)
==1096==    by 0x4007A2C: _dl_map_object (in /lib64/ld-2.10.1.so)
==1096==    by 0x400199A: map_doit (in /lib64/ld-2.10.1.so)
==1096==    by 0x400D495: _dl_catch_error (in /lib64/ld-2.10.1.so)
==1096==    by 0x400189E: do_preload (in /lib64/ld-2.10.1.so)
==1096==    by 0x4003CCD: dl_main (in /lib64/ld-2.10.1.so)
==1096==    by 0x401404B: _dl_sysdep_start (in /lib64/ld-2.10.1.so)
==1096==    by 0x4001471: _dl_start (in /lib64/ld-2.10.1.so)
==1096==    by 0x4000BA7: (within /lib64/ld-2.10.1.so)
* large block of similar snipped *
==1096== Use of uninitialised value of size 8
==1096==    at 0x4F35FDD: (within /lib64/libc-2.10.1.so)
==1096==    by 0x4F35B11: (within /lib64/libc-2.10.1.so)
==1096==    by 0x4A1E61C: _vgnU_freeres (vg_preloaded.c:60)
==1096==    by 0x4E5F2E4: __run_exit_handlers (in /lib64/libc-2.10.1.so)
==1096==    by 0x4E5F354: exit (in /lib64/libc-2.10.1.so)
==1096==    by 0x4E48A2C: (below main) (in /lib64/libc-2.10.1.so)
==1096==
==1096== ERROR SUMMARY: 3819 errors from 298 contexts (suppressed: 876 from 4)
==1096== malloc/free: in use at exit: 0 bytes in 0 blocks.
==1096== malloc/free: 0 allocs, 0 frees, 0 bytes allocated.
==1096== For counts of detected errors, rerun with: -v
==1096== Use --track-origins=yes to see where uninitialised values come from
==1096== All heap blocks were freed -- no leaks are possible.

你可以在这里看到完整的结果：http://pastebin.com/gcTN8xGp

我有两个问题:第一，有没有办法抑制所有的噪音？

--show-after main默认设置为no，但似乎没有--show-after-main等效项。

Answer 1

升级到Valgrind 3.5.0或更高版本。其中，默认的.supp文件已经更新。

Answer 2

可以通过追加以下内容来取消输出

{
   ld error suppression
   Memcheck:Cond
   fun:dl_main
   fun:_dl_sysdep_start
   fun:_dl_start
   obj:/lib64/ld-2.10.1.so
}

到/usr/lib/valgrind/default.supp (或定义您自己的抑制文件)。

这似乎是一个已知的链接器/加载器错误，至少对Debian和Arch Linux开发人员来说是这样；我不确定其余的，以及他们计划的行动方案。

Answer 3

我有时会有这些症状，解决方案总是升级我的valgrind和libc包，使其与同步。Debian的小精灵们会照顾好剩下的事情。