System Calls
Q.1: What is the purpose of System Calls?
Answer:
The purpose of the system calls is to allow user-level applications access of the services provided by the kernel. The user apps do not have the privelege to perform operations, so they make system calls which further requests a kernel to provide a specific service.
Q.2: How do device management System Calls work?
Answer:
Device management system calls work by allowing a certain process or a device interact and get access to other hardware resources and perform various operations.
Q.3: What is user mode and kernel mode?
Answer:
User mode and kernel modes are two different privilege modes of a Computer System, that separates the execution of operations by the user applications and the kernel on hardware. This separation provides security, stability, and a level of control over system resources.
Q.4: What happens when a System Call is executed?
Answer:
When a system call is executed, a context switch occurs and the computer system switches from user mode to kernel mode and now the kernel performs the desired operation.
Q.5: What is a software interrupt?
Answer:
A software interrupt is a mechanism through which the OS performs a context switch and transition from user mode to kernel mode. A software interrupt use is not limited only to the system calls but it can also be made when a high priority task is required to be executed by the CPU.
Different Types of System Calls in OS
System calls are interfaces provisioned by the operating system to allow user-level applications to interact with low-level hardware components & make use of all the services provided by the kernel, which is a core component and the heart of an operating system that manages all the hardware and the services provided by the OS. These system calls are essential for every process to interact with the kernel and leverage the services provided by it.
System calls are basically an interface between a process and the operating system. And they’re the only way to switch from user mode to kernel mode.
Pre-requisite: Introduction to System Calls