"Boot loader didn't return any data" following Xen Guide

[asdf32]

Hi,

I have an Ubuntu 12.10 install. I followed the Xen Guide at https://help.ubuntu.com/community/Xen about two weeks ago and found everything worked fine. I then tried again recently (another completely clean setup), and found I was unable to start the Ubuntu guest VM, receiving "Error: Boot loader didn't return any data".

I think the only difference is that the second time I did an "apt-get upgrade" before starting the Xen Guide. There seems to be a bug reported:

https://bugs.launchpad.net/ubuntu/+s...b/+bug/1094247

It sounds like pygrub can't handle the submenu blocks, although removing the submenus didn't seem to work for me - pygrub still doesn't find the kernel when I run pygrub directly, pointing it at the root partition of the guest. Is anyone else seeing this issue?

Iain

[asdf32]

Just did a clean install again without doing an upgrade and the same error occurs, so probably not due to the upgrade.
- The "sudo xm create<configfile> -c" gives "Error: Boot loader didn't return any data".
- Looking in /var/log/xen/xend.log the error is repeated, but I can see it is running pygrub pointing at the LVM volume for the guest.
- Running pygrub manually gives "RuntimeError: Unable to find partition containing kernel". This is caused by an exception when parsing the Grub configuration "invalid literal for int() with base 10: ..."

It looks like there are some problems in the scripts called by pygrub. In the Grub2ConfigFile I think the title_match should be minimal '^menuentry ["\'](.*?)["\'] (.*){', otherwise it gets the title of the configuration wrong. Then in GrubDiskPart it assumes that everything after the first two characters in the "root" assignment in grub.conf is a number (why would this be?) Just sticking a try/catch around this allows it to proceed a bit further, and I can get pygrub bringing up a menu, but I'm still not able to boot the guest.

Is there a problem with having LVM inside the LVM volume set aside for the guest? (Looking online it appears other people seem to be able to do this?)

[asdf32]

The issue appears to be using LVM in the guest. Works fine without.