Anybody know any tricks to diagnosing why a pv-grub kernel fails to boot on my node?

I transplanted the working config from a 2.6.31.5 and trying to build 2.6.32.2. It gets to the grub menu but after selecting that kernel it kicks me back to LISH.

Meh, seems either the running config in /proc/config.gz or some mix of options when running oldconfig reset some of the xen required options like xen_balloon, re-checking the list, and re-enabling them let the box boot up.

Meh