title: System call and context switch
body: <p>I am sorry to ask this question when it has already been asked but I couldn't get a clarity from them. So I am asking the following related questions to get the difference between system call (mode-switch) and context switch </p>
  
  <ul>
  <li><p>Why is it said that the system call doesn't require context switch when the context of the 
  process making the call has to be saved and then reloaded. Is it just because according to the definition of context switch a switch has to be made to another process.</p></li>
  <li><p>What does it mean that when a system call is made the kernel executes in "user context".</p></li>
  <li><p>According to the wikipedia article : <a href="http://en.wikipedia.org/wiki/Context_switch" rel="noreferrer">http://en.wikipedia.org/wiki/Context_switch</a></p></li>
  </ul>
  
  <p>a context switch is not necessary for system call but it depends on the operating system and a context switch might occur during a system call. I am wondering what would happen in the case when the context switch takes place at the time of system call. Any examples?</p>