title: What does this gdb warning mean? I get it when I try to dump backtrace for a core file
body: <p>I saw this nifty one liner for gdb to dump out backtrace for all threads after a core dump. So I tried a quick:</p>
  
  <pre><code>int main() {int* x = new int[5]; for(int i = 0; true; ++i) x[i] = i; }
  </code></pre>
  
  <p>to get a core dump and then ran this:</p>
  
  <pre><code>gdb --batch --quiet -ex "thread apply all bt full" -ex "quit" a.out core.box-name.a.out.27459.8515.11
  </code></pre>
  
  <p>And I get the output:</p>
  
  <pre><code>[New LWP 27459]
  
  warning: Can't read pathname for load map: Input/output error.
  
  warning: no loadable sections found in added symbol-file system-supplied DSO at 0x7fff9e503000
  Core was generated by `./a.out'.
  Program terminated with signal 11, Segmentation fault.
  #0  0x00000000004005ca in main () at &lt;stdin&gt;:6
  6       &lt;stdin&gt;: No such file or directory.
  
  Thread 1 (LWP 27459):
  #0  0x00000000004005ca in main () at &lt;stdin&gt;:6
          i = 33788
          x = 0x1a460010
  </code></pre>
  
  <p>I see a backtrace which is nice, but am wondering what the two warnings I also see are about?</p>