title: Is xen dom0 a guest or a host?
body: <p>I always thought that xen dom0 is a host and hosts other domU s. </p>
  
  <p>On the <a href="http://wiki.xen.org/wiki/Dom0" rel="nofollow">xen wiki page</a> they mention xen dom0 as a Host OS.</p>
  
  <p>However in <a href="http://www.gossamer-threads.com/lists/xen/devel/299922" rel="nofollow">one of the xen dev list threads</a>, xen developer mentioned that dom0 is a PV guest.</p>
  
  <p>In this thread the last reply on the thread is </p>
  
  <p>"<em>Yes. That is expected with HVM guests. Their syscall overhead and also memory 
  bandwith will be faster than <strong>PV guests (which is what dom0 is).</strong> 
  That is why PVH is such an intersting future direction - it is PV with HVM 
  containers to lower the syscall overhead and memory page table operations.</em> "</p>
  
  <p>So my question is:</p>
  
  <ol>
  <li>Is xen dom0 a guest or host ?</li>
  <li>If it is a guest then is there a HVM dom0 ? </li>
  </ol>