The Women in Computer Science Undergraduate Committee invites you to attend this term's public lecture in which we will host Sarah Sharp, Linux kernel developer and USB 3.0 driver author. Sarah will provide a deep dive into how USB 3.0 support was added to the Linux kernel, as an example of the technical, social, and cultural challenges in getting involved in open source development. Sarah will also provide tips for getting involved with the Linux kernel community.

1. Breaking into Open Source and Linux:
A USB 3.0 Success Story
Sarah Sharp
http://sarah.thesharps.us
University of Waterloo
Nov 20,2014

2. https://cs.uwaterloo.ca/wics
wics-ugrad@uwaterloo.ca

3. Sarah Sharp: Today
Photo copyright LWN: http://lwn.net/Articles/568298/

4. "We struggle with insecurity because
we compare our behind-the-scenes
with everyone else's highlight reel."
http://alistapart.com/column/seeing-past-the-highlight-reel

5. Sarah Sharp: 12 years ago

6. Sarah Sharp: College
● Portland State University
● Met ECE Professor Doug Hall
● Learned how to program
● My boyfriend introduced me to
– open source, Linux, rockets

7. Portland State Aerospace Society

8. Rockets and Open Source

9. Sarah Sharp: College
● Met CS Professor Bart Massey
● ECE senior capstone:
USB-based sensor nodes for PSAS rocket
● Class credit:
microprocessor pin-out combinatorial search

10. Lesson 1:
Rules can be bent

11. Sarah Sharp: College
● Bart introduced me to
– The local Linux kernel community
– Greg Kroah-Hartman
● Greg suggested usbfs2 project
● Bart helped me get:
– ECE elective credit
– Intel undergraduate research grant

12. Lesson 2:
Find a mentor and
do hands-on projects

13. USB filesystem (usbfs)
USB device driver
usbfs
USB core
USB host controller
userspace
kernel

14. usbfs2
● Goal: replace IOCTLS with read/write syscalls
● Didn't want to make userspace block
● Needed asynchronous completion
● Why not use ASYNC I/O?

15. Lesson 3:
Technical Debt

16. Sarah: Senior year
● Bart encouraged me to present at
OSCON on usbfs2
● Kristin Accardi was on OSCON
paper selection committee

17. Characteristics of a
good open source developer
● Meticulous
– Double checks work, addresses feedback
● Excellent communication skills
– Clear, concise, persuasive, responsive
● Self learner, curious, asks questions
● Prefers to work in an open manner

18. Lesson 4:
Grow your network

19. Sarah: Linux USB 3.0 developer
● Hired by Intel in July 2007
● USB 3.0 specification draft
● Hardware was still in FPGA form

20. Linux USB Stack
USB device driver
USB core
USB host controller
userspace
kernel

21. USB device topology
Configuration
Interface
Alternate Setting
● Endpoints:
● IN or OUT
● Buffer Size
● Interval

22. USB 3.0 host changes
● USB 1.1/2.0 hosts
– scheduling done in software
– unaware of device endpoints
● USB 3.0 host
– supports virtualization
– scheduling done in hardware
– must be aware of device endpoints

23. Linux USB Stack
USB device driver
USB core
USB host controller
userspace
kernel

24. Linux USB Maintainers
USB 1.1 host and
USB core
USB 2.0 host USB device drivers and
power management
USB subsystem

25. What is being a
Linux kernel maintainer like?
● Ten to hundreds of emails a day
● Very rapid development cycle
● Looking at long-term health of the project
● Maintains code for 5 - 20 years
● Reputation is on the line for each patch

26. Linux kernel code submission
● Many revisions (often up to v8)
● Must meet coding style standards
● Must be complete and maintainable
● Often old code needs to be refactored
● Can't break other users, subsystems

27. Lesson 5:
Open source is
social and technical

28. Sarah Sharp: Kernel maintainer
● xHCI driver was accepted in 2009
– two years after I was hired
● USB 3.0 kernel maintainer
● Learned about:
– reviewing other people's code
– working with bug reporters
– sending pull requests
– stable backports

29. Sarah Sharp: Conference Speaker
● Uploaded USB 3.0 demo video to reddit
● Articles published about Linux getting USB 3.0 support
before Windows
● Spoke or demoed at numerous conferences
– SuperSpeed Developer Conference Japan 2010
– Linux Conference Australia 2010, 2011, 2013
– Libre Software Meeting (France) 2011
– LinuxCon (North America & Europe)
– OSCON, Open Source Bridge (Portland)

30. Lesson 6:
Promote yourself

31. Sarah Sharp: Today
Photo copyright LWN: http://lwn.net/Articles/568298/

32. Linux Kernel Resources
● Linux Device Drivers book:
http://lwn.net/Kernel/LDD3
● Linux Device Driver tutorial:
https://github.com/gregkh/kernel-tutorial
● First kernel patch tutorial:
http://kernelnewbies.org/FirstKernelPatch
● FOSS Outreach Program for Women (OPW)
(paid open source and Linux kernel internships)
http://gnome.org/opw

33. Photo Attribution
● Kernel Panel: http://lwn.net/Articles/568298/
● Rainier: https://www.flickr.com/photos/misternaxal/513732031
● Dusty computer: https://www.flickr.com/photos/garhol/4417674619
● PSAS photos CC BY-SA-NC Sarah Sharp
● Bart Massey: https://www.flickr.com/photos/igalko/7570219768
● OSCON sign: https://www.flickr.com/photos/kubina/912778997
● Logitech webcam: https://www.flickr.com/photos/bshunrichs/162199777
● Greg Kroah-Hartman: https://www.flickr.com/photos/tian2992/6208491794
● David Brownell:
https://www.flickr.com/photos/13825348@N03/sets/72157608741347102/d
etail/