How to solve "Device 0 (vif) could not be connected. Hotplug scripts not working."?

When starting a virtual machine, xm shows:

Device 0 (vif) could not be connected. Hotplug scripts not working.

Why does开发者_开发知识库 xm show this? How to solve it?

From the Xen wiki:

Error: Device 0 (vif) could not be connected. Hotplug scripts not working.

This problem is often caused by not having "xen-netback" driver loaded in dom0 kernel.

The hotplug scripts are located in /etc/xen/scripts by default, and are labeled with the prefix vif-*. Those scripts log to /var/log/xen/xen-hotplug.log, and more detailed information can be found there.

http://wiki.xen.org/wiki/Xen_Common_Problems

As weird as it sound, I encountered this error in a situation where the sum of vm memory I assigned left the dom0 with too little memory to complete the addition of a virtual interface. Sizing down the virtual machines was the solution.

I agree with PypeBros. Once I put a new entry in /etc/fstab to mount /tmp as tempfs and allocate 10G memory to it. Then the Xen guest won't start and gives me this error:

Error: Device 0 (vif) could not be connected. Hotplug scripts not working.

It worked fine when I removed /tmp as tempfs. So I think this error could be due to memory problem.