[CentOS-virt] Xen HVM domU won't start since updates to 2.6.18-164.15.1 kernels

Sun Mar 28 19:36:59 UTC 2010
Pasi Kärkkäinen <pasik at iki.fi>

On Sun, Mar 28, 2010 at 12:45:58PM -0400, Aaron Clark wrote:
> On 03/28/2010 07:59 AM, Pasi Kärkkäinen wrote:
>> On Sat, Mar 27, 2010 at 11:53:41PM -0500, Christopher G. Stach II wrote:
>>> ----- "Aaron Clark"<ophidian at ophidian.homeip.net>  wrote:
>>>> What steps should I take next to debug this?
>>> Downgrade back to where you were bit by bit (or just guess that it's dom0's kernel) and see when it starts working again.
>>> What does the busted guest say when it tries to boot while you watch its [serial] console? Does the dom0 ever unpause the guest? (It should say in the logs.)
>> Yeah, and remove the vfb (graphical vnc console) from the guest,
>> so you can then do:
>> xm create -f /etc/xen/guest -c
>> to immediately attach to the console and see the guest kernel boot messages.
> Ok, I've tried the following now:
> - rebooted the dom0 into the previous, working kernel-xen and start domU  
> (doesn't work)
> - while in the old kernel-xen, switch the grub config for the domU to  
> use the old kernel then try to start the domU (doesn't work)
> - remove the vnc lines from the guest's config via virsh edit and  
> attempt to start (doesn't work)
> I do not have any serial console stuff set up, so I'll need a little bit  
> more detailed instructions to get that working (which files I need to  
> modify on guest and host, what to put where, etc).

You don't need a serial console to see the _guest_ kernel boot messages.
You just disable vfb (graphical console) from the guest, and then the 
guest kernel messages will automatically go to the Xen text console:

You can see the full guest kernel boot messages like this:

xm create -f /etc/xen/<guest> -c

Edit the /etc/xen/<guest> cfgfile first, and remove the vfb line to disable graphical console.

> I have attached the snippet of the xend.log from my latest startup  
> attempt and the virsh xml in use while it is 'running' but not actually  
> working.

In your xml config there still was graphical console configured.

-- Pasi