[CentOS-virt] xenbr0 isn't created anymore

Wed Apr 2 13:31:17 UTC 2008
Kai Schaetzl <maillists at conactive.com>

Richard Chapman wrote on Wed, 02 Apr 2008 20:41:33 +0800:

> I notice that libvirtd is running - and is set to run on boot. Should 
> this be the case when running the non xen kernel?

No. It gets pulled in when you update to CentOS 5.1 and have xen packages 
installed I assume. You do not need it at all, xen or not. But it provides 
some functionality if you are running xen, so it depends if you need it or 
not. But if youa re not running xen you can shut it off.

> Should I set libvirtd to not start on boot. This might get rid on 
> dnsmasq - but is it a safe and good thing to do in my case?

Yes. "service libvirtd stop" and "chkconfig libvirtd off" will do this. If 
you ever happen to need it with xen (Ross and I had some conversation 
about libvirtd here recently, this should give you an idea) you can get it 
back with the "start" and "on" parameters for the two commands mentioned.
For dnsmasq you have to do a "killall dnsmasq" as it wasn't started via 
the init.d script.

> Is there anything else I need to prevent from starting to eliminate all 
> traces of xen?

I don't know if xend starts or even can start if you are not running a 
xen-kernel. So, you could check if xend is running. livirtd in itself is 
not xen, just a "helper" for various VM API's. And it starts dnsmasq to 
provide DHCP for the virtual network of the VMs as this seems to be quite 
complex as you can see in this thread.

So, if you do like above you haven't eliminated "all traces of xen", but 
there's nothing active related to it and you can switch to it any time 
later again. I would only uninstall the xen packages if you are absolutely 
sure that you won't be using xen again.

I find that xen does not interfere with the normal networking at all, the 
only problem was this DHCP problem for the xen VMs themselves. I'm 
surprised that using the other kernel solved whatever problems you had.


Kai Schätzl, Berlin, Germany
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