The recent increase in complexity and functionality in embedded systems makes them more vulnerable to rootkit-type attacks, raising the need for integrity management systems. However, as of today there is no such system that can guarantee the system's safety while matching the low-resource, real-time and multi-core requirements of embedded systems. In this paper, we present a Virtual Machine Monitor (VMM) based monitoring service for embedded systems that checks the actual kernel data against a safe data specification. However, due to the VMM and multi-core nature of the system, the guest OS can be preempted at any time, leading to the checking of potentially inconsistent states. We evaluated two approaches to solve this problem: detecting such invalid states by checking specific kernel data, and detecting system calls using the VMM.