SYSTEM CALLS

1) Provides services of OS to the user program via API (Application Program Interface)
2) When a process in user mode requires access to resource then it requests the kernel to provide the resource via system call
3) System calls are the only entry points into kernel system
4) System call is an interface between applications/processes and Kernel.

WORKING OF SYSTEM CALL

Step 1: The processor executes a process in the user space until a system call interrupts it.
Step 2: Then on a priority basis, the system call is executed in the kernel space.
Step 3: After the completion of system call execution, control returns to user space.
Step 4: The execution resumes in Kernel space.


OPERATING SYSTEM
   • OPERATING SYSTEM  

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