title: Fast kernel recompile
body: <p>I'm trying to automate the process of recompile a upgraded kernel. (I mean version upgrade)</p>
  
  <p>What I do:</p>
  
  <ol>
  <li><p>Backup the object files (*.o) with rsync</p></li>
  <li><p>Remove the directory and make mrproper</p></li>
  <li><p>Extract new source and patch</p></li>
  <li><p>Restore object files with rsync</p></li>
  </ol>
  
  <p>But I found it doesn't make sense. Since skip compiled things need to get a hash, this should removed it.</p>
  
  <p>Question: What file do I need to keep? or it doesn't exists?</p>
  
  <p>BTW: I already know ccache but it broke with a little config change.</p>