Nachos Projects Overview and Project 1

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Nachos Projects Overview and Project 1

• TA ???
• 2007/10/24

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Outline

• Whats Nachos?
• Why do we use Nachos?
• Nachos Project Overview
• Nachos installation
• Nachos Assignment 1
• Reference

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Whats Nachos?

• Nachos
• Not Another Completely Heuristic Operating System
• Developed by Tom Anderson and his students at UC,
  Berkeley.
• http//www.cs.washington.edu/homes/tom/nachos/

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Whats Nachos?

• Nachos is an instrumental software that allows
  students to study and modify a real operating
  system.
• The only difference between Nachos and a real
  operating system is that Nachos runs a Unix
  process, whereas a real operating system runs on
  a real machine.

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Whats Nachos?

• Nachos simulates a MIPS machine (MIPS R2/3000) on
  the host system (Unix, Linux, etc.)
• Conceptually, Nachos has two modes of execution,
  namely, MIPS simulator and Nachos kernel

Reference http//course.cs.ust.hk/comp252/web07f
all/Lab1/Nachos20architecture/nachos.ps
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Why do we use Nachos?

• For understanding operating system concepts,
  nothing is better than building an operating
  system.
• Nachos is simpler than UNIX.
• Simulator makes debugging easier.
• Deterministic

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Nachos Project Overview

• The project for this course is to build an
  operating system for scratch. The project
  contains four phases, corresponding to each of
  the major pieces of a modern OS.
• Multiprogramming
• Thread management
• File Systems and Virtual Memory
• Networking

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Nachos Installation

• Platforms you may use
• Unix, Linux, Linux over VMware, or Cygwin.
• Environment
• Checking g version
• g -v
• Both g 3.3.3 or g 3.2.2 are ok.
• Get Nachos-4.0
• http//cc.ee.ntu.edu.tw/farn/courses/OS2007/nacho
  s/nachos-4.0.tar.gz
• wget

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Nachos Installation

• Get Cross Compiler
• http//cc.ee.ntu.edu.tw/farn/courses/OS2007/nacho
  s/mips-decstation.linux-xgcc.tgz
• Move Cross Compiler to /
• mv ./mips-decstation.linux-xgcc.tgz /
• Untar Cross Compiler
• cd /
• tar zxvf mips-decstation.linux-xgcc.tgz

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Nachos Installation

• Untar Nachos
• tar zxvf nachos-4.0.tar.gz
• Make Nachos-4.0
• cd ./nachos-4.0/code
• make
• Test
• cd ./userprog
• ./nachos e ../test/test1
• ./nachos e ../test/test2

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Nachos Installation

• You should see the result of test1

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Nachos Installation

• You should see the result of test2

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Some Important Things

• Nachos arguments
• Help
• ./nachos h
• Debugging Mode
• ./nachos s
• Execute files
• ./nachos e file_name
• Recompilation of modified nachos code
• cd nachos-4.0/code
• make clean (optional)
• make

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Nachos Assignment 1

• Abstract
• The assignment is to support multiprogramming. We
  give some of the code you need, and you have to
  complete the system.
• Try execute two programs at the same time on
  Nachos
• cd ./userprog
• ./nachos e ../test/test1 e ../test/test2
• you should see the following result.

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Result of simultaneously execution

• Total threads number is 2
• Thread ../test/test1 is executing.
• Thread ../test/test2 is executing.
• Print integer9
• Print integer8
• Print integer7
• Print integer20
• Print integer21
• Print integer22
• Print integer23
• Print integer24
• Print integer6
• Print integer7
• Print integer8
• Print integer9
• Print integer10
• Print integer12
• Print integer13
• Print integer14

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Result of simultaneously execution

• Print integer18
• Print integer19
• Print integer20
• Print integer17
• Print integer18
• Print integer19
• Print integer20
• Print integer21
• Print integer21
• Print integer23
• Print integer24
• Print integer25
• return value0
• Print integer26
• return value0
• No threads ready or runnable, and no pending
  interrupts.
• Assuming the program completed.
• Machine halting!
• Ticks total 800, idle 67, system 120, user 613

Why the output result of executing two program
simultaneously differs from the result of
executing two programs separately?
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Why should you do?

• Trace Nachos
• Read .h and .cc to understand the whole system
  and see how it is implemented.
• You might use some documentations to help
  yourself understand the system.
• A Road Map Through Nachos
• http//cc.ee.ntu.edu.tw/farn/courses/OS2007/ref/N
  achos20Road20Map.pdf
• Trace for NachoOS-4.0 with GLOBAL
• http//cc.ee.ntu.edu.tw/farn/courses/OS2007/nacho
  s/HTML/index.html

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Hints

• To know why the result is wrong, you may trace
  the following files.
• nachos-4.0/code/userprog/addrspace.h
• nachos-4.0/code/userprog/addrspace.cc
• nachos-4.0/code/userprog/userkernel.cc
• nachos-4.0/code/userprog/translate.h
• nachos-4.0/code/userprog/translate.cc

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Hints

• You have to modify the Nachos code to achieve the
  correct result.
• You may try to modify the following functions
• nachos-4.0/code/userprog/addrspace.cc
• constructor
• destructor
• initRegister
• Load

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Assignment Requirements

• Progress Report (11/7 on the class)
• Prepare a presentation about the following
  topics
• Your understanding about Nachos
• Your progress
• Installation of Nachos
• Knowing why the result is not congruent with
  expected
• Your Plan for modifying Nachos
• Everything you consider important

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Assignment Requirements

• Assignment Report (11/21 on the class)
• Prepare a presentation about the following
  topics
• Why the result is not congruent with expected
• How you modified Nachos to make it support
  multiprogramming important code segments
• Everything you consider important

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Hand in your reports.

• Please compress your code with tar.
• source code only
• tar zcvf r95943071.tar.gz nachos-4.0
• E-mail your code and presentation files(report)
  to TA (mondale.tw_at_gmail.com).
• Deadline 2007/11/21 2359

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Grading Policy

• Progress Report 20
• Correct Result 30
• Report 50

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Reference

• Authors Web Page
• http//www.cs.washington.edu/homes/tom/nachos/
• Thomas Narten's Nachos Roadmap
• http//www.cs.duke.edu/narten/110.html
• Other Reference
• http//www.cse.ucsc.edu/classes/cmp111/Fall94/nach
  os/intro.html
• http//course.cs.ust.hk/comp252/web07fall/nachos_i
  ntro.html
• http//neuron.csie.ntust.edu.tw/homework/93/OS/hom
  ework_2/A9315010/html/