OpenVZ: adding a parameter to GUEST KERNEL.

Hello,

a very short question: how can I add "--verbose" to my GUEST' kernel?

I've already tried by inserting this option in /etc/default/grub file yet I cannot run update-grub because it exit with the following output:

root@VMLAMP01 ~# update-grub
Generating grub.cfg ...
Cannot find list of partitions! (Try mounting /sys.)
done

I build up this GUEST upon a template, ubuntu-10.04-turnkey-lamp_11.3-1_i386.tar.gz.

Please, help me.

Best Regards.