title: accessing xtime variable Linux kernel
body: <p>I am implementing system call that will return the current time of the day (for learning purpose).
  I have looked at implementations of gettimeofday() on Linux 3.19.2
  from the books I checked I got that 
  The current time of day (the wall time) is defined in kernel/time/timekeeping.c:</p>
  
  <pre><code>struct timespec xtime;
  </code></pre>
  
  <p>[Linux kernel development Rober Love]</p>
  
  <p>however I couldn't able to get the xtime variable definition in that file.</p>
  
  <p><strong>where is the xtime variable declared in the Linux kernel and how can I access it from my module or my function?</strong>
  <strong>what are the headers I should  include?</strong></p>