Today I upgraded my virtual machine from Ubuntu 10.04 ‘lucid’ to 11.04 ‘natty’ + 3.0 kernel from 11.10 ‘oneiric’. For first time I used official way for upgrades and did that step by step (lucid -> maverick -> natty) with reboot on each step. Each upgrade ended with reboot of vm.
But fun started when I wanted to install 3.0 kernel from 11.10 ‘oneiric’… Installation went fine — mostly due to [Alex’s comment](http://marcin.juszkiewicz.com.pl/2011/06/20/linux-3-0-under-ubuntu-natty-11-04/#comment-53861) to [my blog post about it](http://marcin.juszkiewicz.com.pl/2011/06/20/linux-3-0-under-ubuntu-natty-11-04/). But after reboot machine did not wanted to boot at all ;(
“`xm create NAME`” resulted in “Error: Boot loader didn’t return any data!” message… After some googling (as I never was XEN administrator) and experiments I got what was wrong. We use ‘py-grub’ to boot VMs and this tool uses “/boot/grub/menu.lst” to get information which kernel to boot. But Ubuntu systems are using “/boot/grub/grub.cfg” due to grub2 instead of grub-legacy.
Anyway I updated menu.lst by hand and VM booted fine. Need to remember for next kernel update 😉