System calls provide the interface between a process and the operating system. These calls are generally available as assembly language instructions
Some systems also allow to make system calls from a high level language, such as C.
Three general methods are used to pass parameters between a running program and the operating system.
- Pass parameters in registers.
- Store the parameters in a table in memory, and the table address is passed as a parameter in a register.
- Push (store) the parameters onto the stack by the program, and pop off the stack by operating system.
- Pass parameters in registers.
- Store the parameters in a table in memory, and the table address is passed as a parameter in a register.
- Push (store) the parameters onto the stack by the program, and pop off the stack by operating system.
<--Types of System Calls-->
-->Process control – load, execute, abort, end, create process, allocate and free memory, wait event etc.
-->File management – Create file, delete file, open, close, read, write, get file attribute etc.
-->Device management – Request device, release device, read, write, logically attach or detach device etc.
-->Information maintenance – Get time and date, set time and date, get process attribute etc.
-->Communications – create, close communication connection, send, receive messages, etc.
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