System call provide an interface between user program and operating system. the system call expose the services that are used by operating system to user programs. most of system call are used in assembly language and machine dependent. also high level language can make system call directly.
The system call interface layer contain entry point in kernel code All system resources managed by kernel any request from user application that involves access to any system resource that must be handled by kernel code .The user must not given open access to kernel for security reason many opening into kernel is called system calls.
Three general methods to pass information
one method is store parameters in registers
another is store parameters in table
The third method is pushed parameters on the stack and pop parameters on the stack
system programs
A system program is an in system program also known as a system software or systems of software
is a type of computer software that provides low-level control and management of the computer hardware
csi503 operating system 2023 gc paper Q1 part3 solution