Linux Kernel Programming

Read Me First

• Everything is in the Web
• Syllabus, lecture notes, reading materials, projects,
• http://www.cs.utexas.edu/users/ygz/378-02S
• Just listen and participate, need not take notes

Who Am I?

• Yongguang Zhang
• Ph.D. in Computer Sciences, 1994, Purdue
• 3rd semester in UT
• Taught 2 grad courses in UTCS
• 4th undergrad courses
• 2 in Purdue-CS, 1 in UCLA-CS
• 1994-2000: Senior Research Scientist at HRL
• Doing basic research for Boeing/Raytheon/GM
• My web site: http://www.cs.utexas.edu/users/ygz

Your TA

• Benjamin C. Hardekopf
• Ph.D. Student in UTCS
• Almost 10 years of experience in Linux
• Will help your learning and grade your projects
• E-mail: benh@cs.utexas.edu

What is this Course About?

• Linux Kernel Programming
• How to work in an example modern OS kernel
• Positioned as the laboratory component in the CS undergrad OS curriculum
• Taken after CS372 (Introduction to OS)
• Comparison to CS372
• CS372: concepts and principles of an OS
• CS378: an example of how they are actually done

What Are We Going to Learn?

• Understanding linux kernel structure
• Know how the kernel works
• Know how to customize kernel
• Writing kernel code
• Experience developing code for OS kernel
• System programming skill
• Ability to deal with large, complex systems.
• Very different from application programming (e.g., using Java)

Why Take This Course?

• Linux is increasingly important -- it is a good skill to have
• You want to become a system programmer
• You want to find a job as a system programmer
• You want to go to graduate school and do systems research

What is This Course NOT for?

• How to use Linux
• You are CS seniors, you should have known by now
• If not, there are lots of books and online resources
• Still no? there are dummy books and training courses
• How to program in Linux
• See above
• Linux certificates
• Those are for technicians
• You are a science student from a top-10 CS department, you don't want those kind of jobs

Prerequisite

• CS372 (introduction to OS)
• CS372: concepts and principles of an OS
• CS378: an example of how they are actually done
• Taking CS372 and CS378 together?
• Possible, but discouraged
• Need to be very initiative and be prepared to spend a lot more time
• Will UTCS repeat this course?
• No definite plan now
• Largely up to you

Course Structure

• Hands-on, Project-oriented
• Lots of programming assignments (9 totals)
• You learn by doing the projects and consulting the books (textbook, references, online resource)
• No exam
• Lectures
• Cover the basics and overview parts of Linux kernel
• Not possible to cover everything in depth
• There will be guest lectures too (by Linux Gurus from industry)

Projects

• 3 Individual Assignments (week 2-4)
• One per week, on basic topics of Linux kernel (that everyone should know)
• 5 Group Projects (week 5-9)
• Each cover different part of the kernel
• 2-3 students per group
• 8 projects will be announced before week 4
• You pick 5 out of 8 projects, and do one per week
• You can change groups for each project
• 1 Final Project (week 11-15)

The Final Project

• A larger project to put all your skills in use
• On an interesting topic, may have practical value, may make contribution to Linux community
• Project list (and group size) will be announced after week 4
• You form a group and pick a project
• Opportunity to do projects with IBM Linux Technology Center
• Many final projects are suggested by IBM LTC
• You can work with mentors from IBM LTC

Lectures

• Part-I: First 4 weeks
• The basics of Linux kernel
• Part-II: Week 5-11
• Overview of different parts of the kernel
• May not cover everything in depth (you will learn them through your projects)
• Part-III: Week 12-14
• Special topics, guest lectures, etc.

Student Strategy

• Part-I: Master the basics
• Lectures, assignments
• Part-II: Come to the lecture and learn the basics
• Part-II: Learn the details through projects
• Start from the project description
• Identify the parts of kernel that the project covers
• Learn those parts by reading the textbook yourself
• Use what your learn in the project
• Bring your questions to class
• Part-III: See above

Example Bad Strategies

• Read the textbook from page 1 to page 684
• This is not a reading class
• Attempt to memorize the code
• In system programming, the skill is more important
• It is good to know the code, but only through practice
• Skip the lectures
• You can learn the parts of kernel that your choice of projects does not cover during lectures
• Attendance counts as 20% of your grade

Expectation from You

• You work hard (approximately 10 hours/week)
• You take initiatives
• You learn the details by yourself
• Don't wait till the last minute to start your project
• You work well with your teammate
• Or you may have no one to work with for next project
• Everything in Linux
• No project, document written with MS Windows

Grades

• 20% Class participation (not just attendance)
• 80% Projects:
• 3 individual assignments: 18% (6% each)
• 5 group projects: 30% (6% each)
• 1 final project: 32%

Course Matters

• Class Meeting Time: Mon/Fri 11:00am-12:30pm
• No class on Wednesday
• Professor Office Hour: Mon/Fri 2:30pm-3:30pm
• Other time please make appointment by e-mail (ygz@cs.utexas.edu)
• TA Office Hour: TBA
• Questions about your projects, Linux kernel: see your TA first

Course Matters

• Textbooks:
• Understanding the Linux Kernel
• Kernel Projects for Linux
• Reference books: ask me
• Online resources
• Many many linux websites
• A good start: www.linux.org, www.kernel.org
• Use google

Course Matters

• Newsgroup
• CS Accounts
• Linux hosts
• cshosts publinux

Today's Short Topics

• Linux history
• System programming

Modern Operating Systems

• Architecture
• Kernel: OS core running in privileged mode
• User-space: compiler, editor, GUI, ..., system and application programs
• Unix
• Many flavors (most not "free")

What is Linux

• Full featured, Unix-like OS
• Open source: entire kernel source available free
• Community: created by a loose worldwide community of programmers collaborating mainly through the internet
• Portable from mainframe to hand-helds
• Estimated users: over 18 millions (counter.li.org)

GNU: Open Source before Linux

• The concept of "free" software
• Through 70s: Richard Stallman advocates "free" software
• "free" as in freedom (not zero cost):
• free to use, distribute (for a profit), and modify
• 1984: Richard Stallman founded GNU
• Goal: to produce free software.
• GPL: ensure software freedom by copyright terms
• GNU software: Unix-like programs (no kernel)

Linux Right on the Start

• 1991: Finnish student Linus Torvalds started working on update of Minix
• From early start, Linus asked for volunteers on the Internet to help him develop Linux
• People started using and publicizing Linux
• A number of programmers joined the project
• From the start, the source code has been freely available on the Internet
• GNU has lots of user-space programs but no kernel

Linux Kernel Evolution

• 0 (Apr 1991): First e-mail from Linus
• 0.01 (Sept 1991)
• 1.0 (March 94), user: 100,000
• 1.2 (March 95), user: 500,000
• 2.0 (June 96), user: 1,500,000
• 2.2 (January 99)
• 2.4 (January 2001)
• Odd/Even versioning system
• 2.4.x: stable kernels
• 2.5.x: development kernels

Systems Programming

• What is System Programming?
• Dealing with large complex and usually monolithic system software (e.g., OS kernel)
• Why large, complex, and monolithic software?
• Structure often limits flexibility and performance
• Working such system requires extraordinary skill
• It is often an art more than a science or an engineering
• In industry
• System programmers usually have more "respect" than application programmers

Today's Homework

• Read Chapter One before coming to class Friday
• Practice using Linux (if you are not familiar with it already)
• Book-marking the course website.

Next Class

• Linux kernel structure
• User-Mode-Linux
• Give you first programming assignment (due next Friday)

Acknowledgement

• This course is in part supported from a grant from IBM Linux Technology Center (Austin)