With the trend to consolidate multiple systems onto the same hardware platform, which can be observed for example in the automotive industry, virtualization of embedded systems becomes increasingly important. Often small and efficient real time operating systems (RTOS) run besides general purpose operating systems (GPOS) with a convenient, high level application interface. When virtualizing embedded reconfigurable systems, FPGA characteristics have to be considered like limited FPGA area and high reconfiguration latencies. We present the FPGA virtualization layer L4ReC that enables the shared usage of reconfigurable resources by several guest operating systems under consideration of the constraints given by embedded reconfigurable systems. First results target isolation, energy efficiency, and FPGA resource management considering special requirements of guest operating systems.