title: what is the difference between PPI, SPI and SGI interrupts?
body: <p>In ARM architecture I have read that there are 3 kinds of interrupt :</p>
  
  <ul>
  <li>PPI - Per processor interrupts</li>
  <li>SPI - Shared processor interrupts</li>
  <li>SGI - Software generated interrupts</li>
  </ul>
  
  <p>I want to know what are these, and how they are different from each other ?</p>