System Calls

SYSTEM CALLS

ü System calls  provide the interface between  a process and  the operating system.

ü These calls are generally available as assembly-language instructions.

ü System calls can be grouped roughly into five major categories:

1. Process control

2. file management

3. device management

4. information maintenance

5. communications.

1.   Process Control

v end,abort

v load, execute

v Create process and terminate process

v get process attributes and set process attributes.

v wait for time, wait event, signal event

v Allocate and free memory.

2. File Management

v Create file, delete file

v Open , close

v Read, write, reposition

v Get file attributes, set file attributes.

3. Device Management

v Request device, release device.

v Read, write, reposition

v Get device attribtues, set device attributes

v Logically attach or detach devices

4. Information maintenance

v Get time or date, set time or date

v Get system data, set system data

v Get process, file, or device attributes

v Set process, file or device attributes

5. Communications

v Create, delete communication connection

v Send, receive messages

v Transfer status information

v Attach or detach remote devices

Two types of communication models

(a) Message passing model

(b) Shared memory model