OS mélange

   

What does an OS do ?

● Resource control/sharing● Resource Policing● Lower layer abstraction● Mechanism Vs Policy

   

OS T i t -b i ts

● Preemptive Multitasking vs Cooperative Multitasking

● OS API vs OS Implementation● Microkernel Vs Monolithic Kernels● Hardware based isolation aka Address

spaces● Posix – Portable Operating System

Interface for Unix

   

Microkerne l OS St ructure

Kernel

Hardware

Severs Servers File System Drivers

   

HURD

● Hurd' stands for `Hird of Unix-Replacing Daemons'. And, then, `Hird' stands for `Hurd of Interfaces Representing Depth'

● GNU's dream OS, started dev in 1990● Used the MACH microkernel● Due to MACH's Performance woes,they

have moved over to L4 very recently● Microkernel Approach

   

HURD

● HURD development never finished● Linux became too popular, most of the

GNU work done came to be used in the Linux Operating System.

● Purist insist on calling such systems GNU/ Linux

   

L4

● MACH, the pioneer of the Microkernel idea had miserable performance

● Extremely low memory footprint● FAST !● Highly optimised● Due to its small size, efforts are on to

prove its correctness formally L4.Sec Project

   

BEOS Screen shot

   

BEOS

● Made in 1991 by BE Inc● Initially ran on ATT hardware● Ported to Power PC in hope Apple would

buy them, but Apple instead went for NextStep

● Failed commercially● Band of loyal supporters have tried to a

complete re-implementation of the BEOS API in “Haiku”

   

Singu lar i ty

● Microsoft Research project● Radically different approach● Software based Isolation● Entire OS written in C#, which is a safe,

managed language● There is just one Address space, isolation

is guaranteed by maintaining invariants in terms of “no cross references” etc

   

Guess the operat ing sys tem ??

   

React OS – Windows Done Right

● Clean room re-engineering of windows API

● GPL● Under heavy development● Currently undergoing a phase of self audit

to ensure complete legality

   

Sy l lab le

● Hobbyist OS gone big● 99% POSIX compliant● Only for x86● Incredibly responsive and fast boot up

– 8 second bootup– 2 second login

   

Future Di rect ions

● Web Only operating systems– Google OS ??

● Virtual Machine based approach– Simulate multiple machines on your machine,

run whatever OS you fancy on each of them (Xen, VMware)

   

Other Notab les

● OS2/Warp● FreeBsd● Minix

   

Images

● Linux Logo: http://www.linux.org/info/logos.html

● GNU Logo: http://www.gnu.org/

● FreeBSD logo: http://en.wikipedia.org/wiki/FreeBSD

● L4 Pistachio Logo:http://l4ka.org/projects/pistachio/

● Hurd logo: http://www.gnu.org/software/hurd/hurd.html

● Syllable logo: http://www.osnews.com/story.php?news_id=7900

● BEOS Snapshot: http://en.wikipedia.org/wiki/BeOS

● ReactOS Snapshot: http://www.reactos.org/en/index.html