title: Does sysfs procfs devtmpfs mounted by kernel?
body: <p>I'm looking into systemd.</p>
  
  <p>I thought systemd would mount sysfs(/sys), procfs(/proc), devtmpfs(/dev) during booting after kernel initialization.</p>
  
  <p>But my systemd debugging log show that systemd doesn't mount such file systems.(it only mounts cgroups, securityfs, etc...)</p>
  
  <p><strong>By when, and whom does such file system is mounted? Does kernel mount sys, proc, dev?</strong></p>