1. Describe the steps executed by a kernel to context-switch between processes.  Compare and contrast two major variations of message passing systems. 
2. Suppose you have a multiprocessor system with 4 equal capability processors. A special-purpose OS is installed in the system. The OS supports multi-threading by providing up to 4 kernel threads per application program and uses many-to-many model to map user threads to kernel threads. The system is currently running only one process. The program is multithreaded and works on square arrays of size at least 3.