By Roddy Rodstein 12/9/2013
This post applies to Oracle VM Server 3.x on Dell PowerEdge R820 Hardware
When installing Oracle VM Server 3.x on Dell PowerEdge R820 servers, after starting the installation, Xen panics with "Panic on CPU 0: queue invalidate wait descriptor was not executed. Reboot in five seconds", and the installation is stopped. This is a known issues with Xen, and can be resolved by adding custom boot commands.