title: Valgrind 'noise', what does it mean?
body: <p>When I used valgrind to help debug an app I was working on I notice a huge about of noise which seems to be complaining about standard libraries.  As a test I did this;</p>
  
  <pre><code>echo 'int main() {return 0;}' | gcc -x c -o test -
  </code></pre>
  
  <p>Then I did this;</p>
  
  <pre><code>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.
  </code></pre>
  
  <p>You can see the full result here:
  <a href="http://pastebin.com/gcTN8xGp" rel="noreferrer">http://pastebin.com/gcTN8xGp</a></p>
  
  <p>I have two questions; firstly is there a way to suppress all the noise?  </p>
  
  <p>--show-below-main is set to no by default, but there doesn't appear to be a --show-after-main equivalent. </p>