title: OsDev syscall/sysret and sysenter/sysexit instructions enabling
body: <p>I am building an 32 bit OS in assembly.<br>
  I have setup the IDT and I am handling program interruptus through <code>int</code> instruction.</p>
  
  <p>How can I enable the <code>syscall</code> and <code>sysenter</code> instructions and how do I handle them/return?<br>
  Is true that <code>syscall</code> instruction isn't supported in 32 bit by Intel processors so I can't use it? 
  Is true that <code>sysret</code> instruction isn't safe?
  Do somewhere exist a tutorial for that?</p>
  
  <p><strong>EDIT</strong>: My main question is how to enable the <code>syscall</code> and <code>sysenter</code> instructions! (No duplication)</p>