System Calls

System calls provide the interface between a running program and the operating system.

• Generally available as assembly-language instructions.
• Languages defined to replace assembly language for systems programming allow system calls to be made directly (e.g., C, 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.

Types of System Calls

Process Control
create/terminate a process (including self)

File Management

Also referred to as simply a file system or filesystem. The system that an operating system or program uses to organize and keep track of files. For example, a hierarchical file system is one that uses directories to organize files into a tree structure.

Although the operating system provides its own file management system, you can buy separate file management systems. These systems interact smoothly with the operating system but provide more features, such as improved backup procedures and stricter file protection.

Device Management
Device Management is a set of technologies, protocols and standards used to allow the remote management of mobile devices, often involving updates of firmware over the air (FOTA). The network operator, handset or in some cases even the end-user (usually via a web portal) can use Device Management, also known as Mobile Device Management, or MDM, to update the handset firmware/OS, install applications and fix bugs, all over the air. Thus, large numbers of devices can be managed with single commands and the end-user is freed from the requirement to take the phone to a shop or service center to refresh or update.

Information Maintenance