This paper presents how we can run a real-time guest OS over a Xen hypervisor.
At first, we need to deal with the scheduling problem.
All the scheduling inside a guest OS should be preserved in terms of real-time schedulability.
Namely, schedulability analysis methodology has to be provided so that we can analytically determine the system is able to finish all the real-time tasks within a given deadlines.
Secondly, the hypervisor should be able to deliver physical interrupt event to guest in a timely manner.
It is essential to provide predictable I/O processing, and time-bounded interrupt handling.
We incorporate the real-time scheduling theory into a real system, which provides the fundamentals of real-time scheduling.
Compositional scheduling theory can be applied so that the virtual machine scheduling at hypervisor guarantees the real-time behavior.
Unfortunately, the theory is not directly applicable to the virtual machine scheduling because it induces a significant overhead.
We provide an algorithm that finds the optimal interface while preserving the real-time properties.
In addition, we elaborate the interrupt processing so that the physical interrupt can be immediately delivered to the guest OS side.
After the event delivery, the real-time guest OS can process it with the minimal performance overhead.