2.1 Operating-System Services 2.2 User Operating-System Interface 2.3 System Calls 2.4 Types of System Calls 2.5 System Programs 2.6 Operating-System Design and Implementation 2.7 Operating-System Structure 2.8 Virtual Machines 2.9 Operating-System Debugging 2.10 Operating-System Generation 2.11 System Boot 2.12 Summary

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To describe the services an operating system provides to users, processes, and other systems.

To discuss the various ways of structuring an operating system.

To explain how operating systems are installed and customized and how they boot.

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Fig. 2.1 A view of operating system services

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user and other system programs

user interface

GUI batch command line

system calls

hardware

operating system

program execution

I/O operations

filesystems

communication

resource allocation

accounting

error detection

protection & securityservices

Command Interpreter Graphical User Interfaces

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Fig. 2.2 Example of how

system calls are used

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Example System Call SequenceAcquire input file name Write prompt to screen Accept inputAcquire output file name Write prompt to screen Accept inputOpen the input file if file doesn't exits, abortCreate out file if file exits, abortLoop Read from input file Write to output fileUntil read failsClose output fileWrite completion message to screenTerminate normally

source file

destination file

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API(Application Programming Interface)

- Win32 API, POSIX API, and Java API

BOOL ReadFile c (HANDLE file, LPVOID buffer, DWORD bytes To Read, LPDWORD bytes Read, LPOVERLAPPED ovl);

return value

function name

parameters

Fig. 2.3 The API for the ReadFile() function

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System-call interface

user application

system call interface

user mode

kernel mode .

.

.

.

.

i

open()

Implementation of open() system call … … return

open()

Fig.2.4 The handling of a user application invoking the open() system call

Windows Unix

Process Control CreateProcess() fork()

ExitProcess() exit()

WaitForSingleObject() wait()

File Manipulation CreateFile() open()

ReadFile() read()

WriteFile() write()

CloseHandle() close()

Device Manipulation SetConsoleMode() ioctl()

ReadConsole() read()

WriteConsole() write()

Information Maintenance GetCurrentProcessID() getpid()

SetTimer() alarm()

Sleep() sleep()

Communication CreatePipe() pipe()

CreateFileMapping() shmget()

MapViewOfFile() mmap()

Protection SetFileSecurity() chmod()

InitlializeSecurityDescriptor() umask()

SetSecurityDescriptorGroup() chown()

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File management-create, delete, copy, rename, print, dump, list, and generally manipulate files and directories

Status information-ask data, time, memory, disk, and user and such information

File modification-create, modify and search the contents of the files

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File management-create, delete, copy, rename, print, dump, list, and generally manipulate files and directories

Status information-ask data, time, memory, disk, and user and such information

File modification-create, modify and search the contents of the files

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Programming-language support-compilers, assemblers, debuggers and interpreters

Program loading and execution-absolute loaders, relocatable loaders, linkage editors and overlay loaders

Communications-create virtual connections among processes, users, and computer systems.

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Design GoalsMechanisms and PoliciesImplementation

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Simple Structure

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Application program

Resident system program

MS-DOS device drivers

Application program

Fig. 2.5 MS-DOS layer structure

Layered Approach

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Fig. 2.6 A layered operating system

layer Nuser interface

layer 1

layer 0hardware

Microkernels

-Mach: remove all nonessential components from the kernel and implement them as system and user-level programs.

-provide a communication facility between the client program and the various services that are also running in user space.

-easy to extend the operating system

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Modules

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Core Solaris kernel

scheduling classes

file systems

loadable system call

executable formats

STREAMS modules

miscellaneous modules

device and bus drivers

Fig. 2.7 Solaris loadable modules

An operating system is designed to run on any of a class of machines at a variety of sites with a variety of peripheral configurations.

SYSGEN(system generation)

-reads from a given file, or ask for information.

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Bootstrap program/loader-a small piece of code which locates the kernel and loads it into main memory, and starts its execution.

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1.Powered up2.IR load a predefined location3.Bootstrap perform a variety of tasks(diagnostics)4.Start the operating system