This document provides an overview of the development of Linux and open source operating systems. It describes how Linux originated from earlier systems like UNIX and how Linus Torvalds released the first version in 1991. It also lists some of the major Linux distributions like Debian, Ubuntu, Fedora and compares characteristics of the Linux kernel to Windows.

1. CHAPTER 2: BASIC OF OPEN
SOURCE OPERATING SYSTEM
Part 1

2.  By the end of this chapter, students will be able to:
1) Describe the development of Linux
2) State the benefits of Linux
3) Compare the characteristics between Linux kernel
and Microsoft Windows kernel
4) State the various Linux distributions

3. 3
 1960, Early stage of computation
 Mainframes are the “computers”
 Innovating idea: Multi-programming & Multi-user
Create a multi-user & multi-program OS
1964, Multics
Multiplexed Information and Computing Service
GE, MIT and AT&T
Standard Operating System for USA government

4. 4
 Many difficulties in Multics development
 1969
AT&T pulled out of Multics
Ken Thompson
A simplified version of Multics  UNIX
Dennis Ritchie
Rewrite the UNIX in C
 AT&T cannot sell the UNIX
UNIX is the first free Operating System

5. 5
 1974
Berkeley University buy a tape of UNIX
Student start code navigation
UNIX is customized and improved
They call the OS as BSD (Berkeley Software Distribution)
 Now
BSD does NOT contain any code of AT&T
BSD 4.4, FreeBDS, NetBSD and OpenBSD

6. 6
 1983, AT&T is splitted  It can sell software
 There is a great market for Operating System
Major hardware vendors need OS
 AT&T is selling UNIX System v4 and licensing it
AIX for IBM, HP-UX for HP, …
 BSD is a real danger for AT&T’s market
BSD is not supported
BSD should not be used in commercial

7. 7
 AT&T sold UNIX as much as possible
Novel bought UNIX code and License
 Novel sold the code and license after 2 years
Santa Cruz Operating System
 Microsoft developed Xenix
Based on UNIX VIII
It was NOT successful

8. 8
 1983, GNU project was started by Stallman
 The goal is creating free UNIX-like
 GNU’s kernel Hurd cannot attract attentions

9. 9
 Tanenbaum developed free OS
 Its name is Minix
 Minix is based on UNIX
 Source code available, Modification is restricted
 It cannot run on 32bit processors

10. 10
 Develop a free OS for 32bit (Intel) processors
Title of a Finnish student’s MS thesis
 The student is Linus Benedict Torvalds

11. 11
 Birthday
25 August 1991
Linux 0.02
It was developed in MINIX
It run on 80386 (32bit microprocessor)
It had a terminal emulator & C compiler
Linus posted the code to Minix mailing list
He requested feedback

12. 1) Reliability
 The majority of Linux variants and versions are notoriously
12
reliable and can often run for months and years without
needing to be rebooted.
2) Scalability
 Support Wide Range of Hardware
-Less memory

13. 3) Security
Linux programs are designed to operate in a more secure
manner as isolated processes.
Email attachments can’t be executed automatically, as are
ActiveX controls and other specially built virus files.
Linux (and Mac OS X) prevent any real damage occurring on
a system unless the user is logged in with the highest levels
of permissions as root or administrator.

14. Kernel???
 Kernel is the main component of most computer operating
systems; it is a bridge between applications and the actual data
processing done at the hardware level.
14
A kernel connects the application software to
the hardware of a computer

15.  Both Linux and Windows are monolithic
All core operating system services run in a shared address
space in kernel-mode
All core operating system services are part of a single
module
Linux: vmlinuz
Windows: ntoskrnl.exe
 Windowing is handled differently:
Windows has a kernel-mode Windowing subsystem
Linux has a user-mode X-Windowing system
15

16. 16
Device
Drivers
Application
Linux
Process Management,
Memory Management,
I/O Management, etc.
X-Windows
System Services
Windows
User Mode
Kernel Mode
Hardware Dependent Code
Device
Drivers
Process Management,
Memory Management,
I/O Management, etc.
Win32
Windowing
Application
System Services
User Mode
Kernel Mode
Hardware Dependent Code

17.  Linux is a monolithic but modular system
All kernel subsystems form a single piece of code with no
protection between them
 Modularity is supported in two ways:
Compile-time options
Most kernel components can be built as a dynamically loadable
kernel module (DLKM)
17
 DLKMs
Built separately from the main kernel
Loaded into the kernel at runtime and on demand (infrequently
used components take up kernel memory only when needed)
Kernel modules can be upgraded incrementally

18.  Windows is a monolithic but modular system
No protection among pieces of kernel code and drivers
 Support for Modularity is somewhat weak:
Windows Drivers allow for dynamic extension of kernel functionality
Windows XP Embedded has special tools / packaging rules that allow
coarse-grained configuration of the OS
 Windows Drivers are dynamically loadable kernel modules
Significant amount of code run as drivers (including network stacks
such as TCP/IP and many services)
Built independently from the kernel
Can be loaded on-demand
Dependencies among drivers can 18
be specified

19.  Both Linux and Windows kernels are portable
Mainly written in C
Have been ported to a range of processor architectures
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 Windows
i486, MIPS, PowerPC, Alpha, IA-64, x86-64
Only x86-64 and IA-64 currently supported
> 64MB memory required
 Linux
Alpha, ARM, ARM26, CRIS, H8300, i386, IA-64, M68000, MIPS,
PA-RISC, PowerPC, S/390, SuperH, SPARC, VAX, v850, x86-64
DLKMs allow for minimal kernels for microcontrollers
> 4MB memory required

20. 20
 Windows
Kernel exports about 250 system calls (accessed via ntdll.dll)
Layered Windows/POSIX subsystems
Rich Windows API (17 500 functions on top of native APIs)
 Linux
Kernel supports about 200 different system calls
Layered BSD, Unix Sys V, POSIX shared system libraries
Compact APIs (1742 functions in Single Unix Specification
Version 3; not including X Window APIs)

21. • Linux distributions consists of the Linux kernel (the operating
system) and a collection of applications, together with an
easy-to-use installation program.
• Most people just say Linux to refer to a specific Linux
distribution.
• Each and every one of the Linux distribution includes the
standard Linux operating system and the following major
packages:
– The X Windows System – GUI
– One or more graphical desktop – among the most popular are GNOME
or KDE
– A selection of application – Linux programs come in the form of ready-to-
run software, but the source code is included (or easily available).

22. 1) Fedora Core
Official website:
wwwwww.fedoraproject.org

23. 2)Knoppix
Official website:
www.knoppix.org

24. 3) Debian GNU/Linux
Official website:
www.debian.org

25. 4) OpenSUSE
Official website:
www.opensuse.org

26. 5) Ubuntu
Official website:
www.ubuntu.com

27. 6) Slackware
Official website:
www.slackware.com

28. 7) Gentoo
Official website:
http://www.gentoo.org