OS mélange

What does an OS do ?
Resource control/sharing
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Resource Policing
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Lower layer abstraction
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Mechanism Vs Policy
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OS Tit-bits
Preemptive Multitasking vs Cooperative
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Multitasking
OS API vs OS Implementation
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Microkernel Vs Monolithic Kernels
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Hardware based isolation aka Address
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spaces
Posix – Portable Operating System
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Interface for Unix

Microkernel OS Structure
Severs Servers File System Drivers
Kernel
Hardware

HURD
Hurd' stands for `Hird of Unix-Replacing
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Daemons'. And, then, `Hird' stands for
`Hurd of Interfaces Representing Depth'
GNU's dream OS, started dev in 1990
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Used the MACH microkernel
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Due to MACH's Performance woes,they
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have moved over to L4 very recently
Microkernel Approach
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HURD
HURD development never finished
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Linux became too popular, most of the
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GNU work done came to be used in the
Linux Operating System.
Purist insist on calling such systems GNU/
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Linux

L4
MACH, the pioneer of the Microkernel
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idea had miserable performance
Extremely low memory footprint
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FAST !
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Highly optimised
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Due to its small size, efforts are on to
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prove its correctness formally L4.Sec
Project

BEOS Screen shot

BEOS
Made in 1991 by BE Inc
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Initially ran on ATT hardware
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Ported to Power PC in hope Apple would
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buy them, but Apple instead went for
NextStep
Failed commercially
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Band of loyal supporters have tried to a
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complete re-implementation of the BEOS
API in “Haiku”

Singularity
Microsoft Research project
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Radically different approach
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Software based Isolation
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Entire OS written in C#, which is a safe,
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managed language
There is just one Address space, isolation
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is guaranteed by maintaining invariants in
terms of “no cross references” etc

Guess the operating
system ??

React OS – Windows Done
Right
Clean room re-engineering of windows
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API
GPL
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Under heavy development
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Currently undergoing a phase of self audit
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to ensure complete legality

Syllable
Hobbyist OS gone big
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99% POSIX compliant
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Only for x86
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Incredibly responsive and fast boot up
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8 second bootup
–
2 second login
–

Future Directions
Web Only operating systems
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Google OS ??
–
Virtual Machine based approach
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Simulate multiple machines on your machine,
–
run whatever OS you fancy on each of them
(Xen, VMware)

Other Notables
OS2/Warp
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FreeBsd
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Minix
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Images
Linux Logo: http://www.linux.org/info/logos.html
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GNU Logo: http://www.gnu.org/
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FreeBSD logo: http://en.wikipedia.org/wiki/FreeBSD
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L4 Pistachio Logo:http://l4ka.org/projects/pistachio/
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Hurd logo: http://www.gnu.org/software/hurd/hurd.html
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Syllable logo: http://www.osnews.com/story.php?news_id=7900
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BEOS Snapshot: http://en.wikipedia.org/wiki/BeOS
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ReactOS Snapshot: http://www.reactos.org/en/index.html
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