Describe Three General Methods for Passing Parameters to the Operating System

Describe three general methods for passing parameters to the operating system. Passing parameters to the kernel for a system call must be performed differently than when using an ordinary functional call. This is because a system call is performed by the kernel itself, which typically runs in a completely different address space than the process which made the call. Thus it is not possible to simply place system call parameters onto the process’ stack as this will not be readily available to the kernel. There are three main methods to pass the parameters required for a system call: • • • Pass the parameters in registers (this may prove insufficient when there are more parameters than registers). Store the parameters in a block, or table, in memory, and pass the address of block as a parameter in a register. This approach is used by Linux and Solaris. Push the parameters onto a stack; to be popped off by the OS. Block and stack methods do not limit the number or length of parameters passed. What is the main advantage of the microkernel approach to system design? How do user programs and system services interact in a microkernel architecture? What are the disadvantages of using the microkernel approach? Advantages: Adding a new service does not require modifying the kernel. It is more secure as more operations are done in user mode than in kernel mode. A simpler kernel design and functionality typically results in a more reliable operating system. Interaction: User programs and system services interact in microkernel architecture by using inter process communication mechanisms such as messaging. These messages are conveyed by the operating system. Disadvantages: The primary disadvantages of the microkernel architecture are the process communication and the frequent use of the operating system’s messaging to interact with each other. What are the two models of inter-process communication? What are the strengths and weaknesses of the two approaches? • • • • Shared memory communication is faster the message passing mode lwhen the processes are on the same machine. Weaknesses: o Different processes need to ensure that they are not writing to the same location simultaneously. o Processes that communicate using shared memory need to address problems of memory protection and synchronization. Message-passing model is easier to implement than the shared memory model Weakness: o Communication using message passing is slower than shared memory because of the time involved in connection setup How could a system be designed to allow a choice of operating systems from which to boot? What would the bootstrap program need to do? Consider a system that would like to run both Windows XP and three different distributions of Linux (e.g., RedHat, Debian, and Mandrake). (which we will ) will . It is this boot manager that is responsible for determining which system to boot into. Typically boot managers must be stored at certain locations of the hard disk to be recognized during system startup. Boot managers often provide the user with a selection of systems to boot into; boot managers are also typically designed to boot into a default operating system if no choice is selected by the user. What are the advantages and disadvantages of using the same system call interface for manipulating both files and devices? Using the same system calls in order to manipulate both files and devices would result in the devices being accessed as a file in the file system. with using the same interface is that it might be , thereby either resulting in a or Why do some systems store the operating system in firmware, while others store it on disk? Embedded systems tend to do that because the programs and operating system are not intended to be updated very often - and when they do it requires rather extensive operations to make that possible.