Os Process Management Questions Medium
A system call is a mechanism provided by an operating system that allows user-level processes to request services from the kernel. It acts as an interface between the user-level applications and the operating system, enabling them to perform privileged operations that are not directly accessible to user programs.
When a user-level process needs to perform a specific operation that requires kernel-level privileges, it makes a system call. This can include tasks such as creating or terminating processes, accessing files, allocating memory, or interacting with hardware devices. The system call provides a way for the process to transfer control from user mode to kernel mode, where the requested operation can be executed.
To use a system call, the process typically invokes a specific function or instruction provided by the operating system. This function or instruction triggers a software interrupt, causing the processor to switch from user mode to kernel mode. The interrupt transfers control to a predefined location in the operating system, known as the system call handler.
The system call handler then examines the request made by the process, validates it, and performs the necessary operations on behalf of the process. Once the operation is completed, the control is transferred back to the user-level process, allowing it to continue its execution.
System calls provide a controlled and secure way for user-level processes to interact with the operating system. They ensure that privileged operations are performed only by authorized processes and prevent unauthorized access to critical resources. System calls also enable the operating system to enforce security policies, manage resources efficiently, and provide a standardized interface for application developers to utilize the capabilities of the underlying operating system.