Hello Wei, For systemd/xendriverdomain.service.in, the hardcoded PID file could be removed altogether -- systemd has no trouble figuring out the PID with only one process. But I wasn't sure if maybe something outside of the xen tree uses it? (Sorry that you're not getting my CCs: "554-SMTP.EU.CITRIX.COM 554 You are being rejected because your senderbase score is below our accepted policy. If you have any questions about your senderbase score, please goto http://www.senderbase.org" -- they don't like mail.openmailbox.org for some reason) Rusty