CPSC 405 Lecture: O/S overview

Overview

* What's a computer
  - Draw a diagram in your notebook.
  - Someone draw theirs on the board.

* What's an operating system?
  - List OS attributes in your notebook.
  - Ask individuals for an attribute.
  [user/kernel diagram]
  - h/w: CPU, RAM, disk, net, &c
  - user applications: sh, cc, DB, &c
  - kernel services: FS, processes, memory, network, &c
  - system calls

* What is the purpose of an O/S?
  - Multiplex the hardware among many applications
  - Isolate applications for security and to contain bugs
  - Allow sharing among cooperating applications
  - Abstract the hardware for portability
  - Provide useful services

* Design tensions make O/S design interesting
  - efficient vs abstract/portable/general-purpose
  - powerful vs simple interfaces
  - flexible vs secure
  - compatible vs new hardware and interfaces

* You'll be glad you took this course if you...
  * are curious about how computer systems work
  * need to track down bugs or security problems
  * care about high performance

Class structure

* Online course information:
  web site -- schedule, assignments, labs
    https://gusty.bike/xv6index.html
  Discord -- announcements, discussion, lab help

* Lectures
  * O/S ideas
  * case study of xv6, a small O/S, via code and xv6 book
  * lab background
  * O/S papers
  * You can submit questions about readings on Discord - channel lecture-quesions

* Labs: 
  The point: hands-on experience
  Mostly one every two weeks
  Three kinds:
    Systems programming (due next week...)
    O/S primitives, e.g. thread switching.
    O/S kernel extensions to xv6, e.g. network.
  For help:
    Be in class for the start of labs
    Ask questions in class
    Ask questions on Discord
    Ask questions during office hours
    Arrange for a Zoom meeting and ask questions
  Programming Problems - solution must be yours
  Questions - you can get help from anyone
* Grading:
  50% labs
  25% midterm exam
  25% final exam