Troubleshooting

This page covers common problems when running Xen and how to diagnose them.

Tip

If you cannot resolve a problem on your own, the xen-users mailing list is the best place to ask for help. Include as much diagnostic information as possible.

Diagnosing problems

Start with xl list to see which domains are running and their state. The state column uses single letters: r (running), b (blocked/idle), p (paused), s (shutdown), c (crashed).

Check the Xen log for errors:

xl dmesg

Also check dom0 kernel messages:

dmesg | grep -i xen

Useful log files:

  • /var/log/xen/ — Xen-specific logs

  • /var/log/xen/xen-hotplug.log — device hotplug messages

  • /var/log/xen/qemu-dm-<domname>.log — QEMU device model (HVM guests)

  • /var/log/xen/xl-<domname>.log — xl command logs

Guest console logs

For guest boot issues, enable console logging by setting XENCONSOLED_TRACE=guest in your distribution’s Xen configuration file (/etc/sysconfig/xencommons or /etc/defaults/xencommons). Restart xenconsoled and start a new guest. Console output will appear in /var/log/xen/console/guest-<domname>.

Common problems

Guest fails to start

Run xl create -p /etc/xen/myguest.cfg to create the guest in a paused state. If creation fails, the error message will indicate the cause.

Common causes:

  • Wrong path to kernel or disk image

  • Insufficient memory (check xl info for free memory)

  • Missing bridge interface (check brctl show)

Guest crashes or reboots unexpectedly

Check /var/log/xen/ for error messages. If a crash occurred, also look at the host console output and enable noreboot in the Xen boot options to pause on crash.

No network connectivity in guest

Verify the bridge is set up in dom0:

brctl show
ip link show xenbr0

Confirm the vif appears in xl network-list <domname> and that the interface is up inside the guest.

Reporting bugs

If you have found a reproducible bug, please report it. See the Contributor Handbook for guidance on how to report a bug effectively, including what information to include and where to send it.

Note

Security vulnerabilities should be reported privately to security@xenproject.org rather than on the public mailing list.