title: Why my (kernel) GCov doesn't work on linux 3.9?
body: <p>I had done as the "Documentation/gcov.txt" said.</p>
  
  <p>Basic about mime:</p>
  
  <pre><code>$ uname -a
  Linux turf.ivor 3.9.5 #1 SMP Fri Jun 14 00:51:05 CST 2013 x86_64 x86_64 x86_64 GNU/Linux
  
  $ cat /etc/redhat-release
  Fedora release 18 (Spherical Cow)
  
  $ zcat /proc/config.gz | egrep "GCOV_|DEBUG_FS"
  
  CONFIG_GCOV_KERNEL=y
  CONFIG_GCOV_PROFILE_ALL=y
  CONFIG_DEBUG_FS=y
  
  $ mount | grep debugfs
  debugfs on /sys/kernel/debug type debugfs (rw,relatime)
  
  # ls -la /sys/kernel/debug/gcov/ 
  total 0
  drwxr-xr-x  2 root root 0 Jun 14  2013 .
  drwx------ 17 root root 0 Jun 14  2013 ..
  -rw-------  1 root root 0 Jun 14  2013 reset
  </code></pre>
  
  <p>I found nothing but a reset file (an empty file).</p>
  
  <p>As "document" says:</p>
  
  <pre><code> 90 4. Files
   91 ========
   92                                                                                
   93 The gcov kernel support creates the following files in debugfs:
   94 
   95         /sys/kernel/debug/gcov
   96                 Parent directory for all gcov-related files.
   97 
   98         /sys/kernel/debug/gcov/reset
   99                 Global reset file: resets all coverage data to zero when
  100                 written to.
  101 
  102         /sys/kernel/debug/gcov/path/to/compile/dir/file.gcda
  103                 The actual gcov data file as understood by the gcov
  104                 tool. Resets file coverage data to zero when written to.
  105 
  106         /sys/kernel/debug/gcov/path/to/compile/dir/file.gcno
  107                 Symbolic link to a static data file required by the gcov
  108                 tool. This file is generated by gcc when compiling with
  109                 option -ftest-coverage.
  </code></pre>
  
  <p>What should I do? </p>
  
  <p>Does gcov still support latest linux version?</p>
  
  <p>Any advice, and thanks.</p>
  
  <p>`</p>