The system must be protect against unauthorized access, viruses, worms etc. Businesses normally set rules on how the the work gets done, and will use standard operating procedures, called SOPs, as well as a set of policies and procedures to accomplish work predictably and efficiently. Decoupling the mechanism implementations from the policy specifications makes it possible for different applications to use the same mechanism implementations with different policies. The security of the system emphasizes on the authentication process of the system in order to protect the physical resources as well as the integrity of the information stored in the system. Most modern operating systems support IBAC based access control for file systems access and other security related functions. Mechanisms determine how to do something; policies determine what will be done. The answer to your question depends upon the underlying hardware (and sometimes operating system implementation). Shared memory is a more appropriate IPC mechanism than message passing for distributed systems. This means that those mechanisms are likely to better meet the needs of a wider range of users, for a longer period of time [wiki]. I return to that in a bit. Difference Between Policies & Procedures Vs. SOPs. The Mach operating system treats system calls with message passing. Operating System Security Policies and Procedures. List at least three different ways for structuring an operating system. The difference between a program and a process is that a program is an active entity while a process is a passive entity. There are two operating system design principles, which are: (1) Separation of mechanism and policy by implementing flexible mechanisms to support policies, and … 12.3.2 Mechanism versus Policy Another principle that helps architectural coherence, along with keeping things small and well structured, is that of separating mechanism from policy. This can be done by ensuring integrity, confidentiality and availability in the operating system. What is the difference between policy and mechanism? There are difference between the two. This extends to the operating system as well as the data in the system. Policy is different from mechanism. The purpose of an interrupt handler and a system call (and an fault handler) is largely the same: to switch the processor into kernel mode while providing protection from inadvertent or malicious access to kernel structures. Security provides a mechanism to guard the user’s programs and data against the interference caused by an entity or person external to the system. T. Key Differences Between Preemptive and Non-Preemptive Scheduling: In preemptive scheduling the CPU is allocated to the processes for the limited time whereas in Non-preemptive scheduling, the CPU is allocated to the process till it terminates or switches to waiting state. An operating system operates in a similar manner: by scheduling tasks, improving efficiency, reducing delays and wait times (response times to the system), and managing CPU resources better. Every application has different policies for use of the resources and they may change over time so protection of the system is not only concern of the designer of the operating system. Application programmer should also design the protection mechanism to protect their system against misuse. Policies … There are many different types of operating system (OS) security policies and procedures that can be implemented based on the industry you work in.