“噪音”是什么意思?

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

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.

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

--默认情况下,show below main设置为no,但在main之后似乎没有--show。