Operating Systems Question Bank with Answers 08

What is the purpose of system calls in OS? What is the mechanism used to implement system calls?

Question:

What is the purpose of a system call? What mechanism is typically used to implement system calls?

Answer:

System calls are part of most modern operating systems.

A system call is the means by which an application (user-space process) can invoke services within the operating system.

They are typically implemented by using software interrupts or traps: hardware supported instructions which transfer control to a well-defined entry point in the operating system, switching the processor mode to ”privileged" in the process.

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