The prototype implementation was done for RTLinux . As mentioned, RTLinux uses Interrupt Abstraction to make Linux real-time capable. This is a two-kernel solution where Linux runs on top of a real-time scheduler. Hence the Core Runtime environment has to run directly on the real-time scheduler and communication must be possible from the real-time threads to the non-real-time threads running on a standard JVM on top of the Linux kernel. This is implemented by some communication routines that use the FIFOs provided by RTLinux for communication between real-time threads and non-real-time Linux threads. These FIFOs are accessed by native code via JNI (figure 5).