In the slides and videos section below, I will post slides and pre-recorded discussion section videos before 6PM on the day before the live discussion section. In a discussion section video, I will primarily present information regrading up-coming programming assignments. I will also post live discussion section videos there.

Each live discussion section is conducted by a TA. Below is a list showing which TA is responsible for which discussion section:

• Fri 10:00am - 10:50am on Zoom (Zoom meeting ID given in Lecture 0) - Ben Yan
• Fri 12:00pm - 12:50pm on Zoom (Zoom meeting ID given in Lecture 0) - Zhuojin Li

During a live discussion section, the TA will answer questions about the pre-recorded video and answer your questions about programming assignments. If you have a particular topic that you would like the TA to discuss in class (including stuff like something covered in lectures that you would like the TA to explain further), you should send e-mail to the TA before 6PM on Thursday. The TA will try his/her best to cover such requests.

Please note that programming assignments are due on Fridays. Since you are expected to have finished the an assignment before its due date, on the due date of a programming assignment, the TA will be introducint the next programming assignment and that takes priority over the current assignment. If there is time left, the TA can discuss the current assignment.

To download all the PDF files below in one command (so you can study for exams), do the following inside a terminal in Ubuntu 16.04:

    wget -r -l 1 --user=USERID --password=PASSWORD http://merlot.usc.edu/cs402-s21/discussions.html

where USERID and PASSWORD are the user ID and password used to access protected content from our class web site. But please note that the lecture slides can change at any time without notice. Therefore, it's a good idea to re-run the above command often to synchroniza your copy with the server!

The discussion section videos are there to help you with programming assignments. Therefore, it's advisable that you watch the discussion section videos first before you start writing a lot of code! Even though the date of a discussion section may be in the future, if a video is available early, it's useful to check it out as early as possible! This can save you from having to rewrite a lot of code.

It's possible that you may get confused when you watch a discussion section video because you are not familiar enough with the spec and what you are supposed to do. But that's okay! It's important that you have seen the material so that when you are going in the wrong direction, you may be able to stop and review the material again before proceeding. As I have mentioned many times, if you are confused about anything, don't hesitate to ask me! I'm here to help and I cannot help you if you don't ask questions!

(Please note that access to discussion slides and videos are restricted.)

• Week 0 (PDF) (Jan 15, 2021) - information sessions
  • 10am live discussion section - 19 minutes
• Week 1 (PDF) (Jan 22, 2021) - gdb, warmup #1 (part 1)
  • video (part 1 of 1) - 56 minutes
  • live discussion sections
    • 10am live discussion section - 26 minutes
    • 12pm live discussion section - 18 minutes
• Week 2 (PDF) (Jan 29, 2021) - warmup #1 (part 2)
  • video (part 1 of 1) - 49 minutes
  • live discussion sections
    • 10am live discussion section - 47 minutes
    • 12pm live discussion section - 16 minutes
• Week 3 (PDF) (Feb 5, 2021) - warmup #2 (part 1)
  • video (part 1 of 1) - 49 minutes
  • live discussion sections
    • 10am live discussion section - 17 minutes
    • 12pm live discussion section - 12 minutes
• Week 4 (PDF) (Feb 12, 2021) - more on warmup #2, introduction to kernel assignments
  • video (part 1 of 1) - 50 minutes
  • live discussion sections
    • 10am live discussion section - 20 minutes
    • 12pm live discussion section - 49 minutes
• Week 5 (PDF) (Feb 19, 2021) - introduction to kernel assignments
  • video (part 1 of 1) - 51 minutes
  • live discussion sections
    • 10am live discussion section - 12 minutes
    • 12pm live discussion section - 9 minutes
• Week 6 (PDF) [BC: slide 9 fixed in PDF but not in video] (Feb 26, 2021) - kernel 1
  • video (part 1 of 1) - 55 minutes
  • live discussion sections
    • 10am live discussion section - 12 minutes
    • 12pm live discussion section - 45 minutes
• Week 7 (PDF) (Mar 5, 2021) - more on kernel 1 (prerequisite: Lecture 14)
  • video (part 1 of 1) - 50 minutes
  • live discussion sections
    • 10am live discussion section - 8 minutes
    • 12pm live discussion section - 15 minutes
• Week 8 (PDF) (Mar 12, 2021) - introduction to kernel 2 (prerequisite: Lecture 16)
  • live discussion sections
    • video (part 1 of 1) - 52 minutes
    • no live live discussion sections (wellness day)
• Week 9 (TXT) (Mar 19, 2021) - kernel 2 polymorphism, vfs.c, vnode.c, file.c, vfs_syscall.c, vn_mmobj_ops.c, ramfs.c, vfstest.c, faber_fs_test
  • video (part 1 of 1) - 52 minutes
  • live discussion sections
    • 10am live discussion section - 7 minutes
    • 12pm live discussion section - 13 minutes
• Week 10 (PDF) (Mar 26, 2021) - introduction to kernel 3, the elf32 loader
  • video (part 1 of 1) - 60 minutes
  • live discussion sections
    • 10am live discussion section - 4 minutes
    • 12pm live discussion section - 11 minutes
• Week 11 (PDF) (Apr 2, 2021) - more on kernel 3, address space implementation (vmarea, mmobj, pframe, page table)
  • video (part 1 of 1) - 57 minutes
  • live discussion sections
    • 10am live discussion section - 16 minutes
    • 12pm live discussion section - 9 minutes
• Week 12 (TXT) (Apr 9, 2021) - objdump, page fault handling, hello
  • video (part 1 of 1) - 52 minutes
  • live discussion sections
    • 10am live discussion section - 5 minutes
    • 12pm live discussion section - 10 minutes
• Week 13 (TXT) (Apr 16, 2021) - fork(), user space shell
  • video (part 1 of 1) - 52 minutes
  • live discussion sections
    • 10am live discussion section - 4 minutes
    • 12pm live discussion section - 9 minutes
• Week 14 (Apr 23, 2021) - (no discussion video this week)
  • live discussion sections
    • 10am live discussion section - 0 minutes
    • 12pm live discussion section - 1 minutes
• Week 15 (Apr 30, 2021) - (no discussion section this week, university wellness day)

The following are tentative discussion section slides (in PDF format) for this semester. Please note that the source code below is for the purpose of discussions and may not be identical to the code in your assignments. It would be a really bad idea (because you can lose a lot of points) to replace the code in your assignments with the code here!

• Week 0 (PDF) (1/15) - information sessions
• Week 1 (PDF) (1/22) - gdb, warmup #1
• Week 2 (PDF) (1/29) - parsing text input in C, Unix/Linux commands, introduction to warmup #2
• Week 3 (PDF) (2/5) - introduction to warmup #2
• Week 4 (PDF) (2/12) - warmup #2 (catching SIGINT and pthread cancellation), introduction to kernel assignments

  Code in slides:

  • defs.h
  • fork-wait.c
  • cat.c
  • redirect.c
  • thr-term.c
  • busywait.c
  • join.c
  • deadlock.c
  • trylock.c
  • whoopee.c
  • status-update.c
  • sigblock.c
  • sigwait.c
  • direct.c
  • cancel.c
  • three-threads.c

• Week 5 (PDF) - introduction to kernel assignments
• Week 6 (PDF) - kernel 1, kmain.c

  Code (kernel)

  • kmain.c

• Week 7 (PDF) - more on kernel 1, faber_test.c

  Code (kernel)

  • faber_test.c

• Week 8 (PDF) - introduction to kernel 2

  Code (kernel):

  • namev.c (path name resolution code)

• Week 9 (TXT) - kernel 2 polymorphism, vfs.c, vnode.c, file.c, vfs_syscall.c, vn_mmobj_ops.c, ramfs.c, vfstest.c, faber_fs_test

  Code (kernel):

  • vfs.c
  • vnode.c
  • file.c
  • vfs_syscall.c
  • vn_mmobj_ops.c
  • ramfs.c (also look for any "_ops_t" in "kernel/include/fs/*.h", "kernel/fs/*.c" and "kernel/fs/ramfs/*.c")
  • vfstest.c
  • faber_fs_test.c

• Week 10 (PDF) - introduction to kernel 3, the elf32 loader

  Code (kernel):

  • elf32.c - the elf32 loader
  • exec.c
  • access.c

• Week 11 (PDF) - more on kernel 3, address space implementation (vmarea, mmobj, pframe, page table)

  Code (kernel):

  • vn_mmobj_ops.c - code for the mmobj inside a vnode
  • syscall.c (in the kernel)

  
  Code (user):

  • syscall.c (in the libc user space library)

  
  Kernel 3 FAQ:

  • meaning of pagenum

• Week 12 (TXT) - objdump, page fault handling, hello

  Code (kernel):

  • pagefault.c
  • syscall.c (in the kernel)
  • vn_mmobj_ops.c - code for the mmobj inside a vnode

  
  Code (user):

  • hello.c
  • syscall.c (in the libc user space library)

  
  Kernel 3 FAQ:

  • handle the first page fault
  • meaning of pagenum
  • page faults

  
  Useful Linux commands:

      objdump --disassemble --section=".text" user/usr/bin/hello.exec
      objdump --disassemble --section=".text" -S user/usr/bin/hello.exec
      objdump --headers user/usr/bin/hello.exec
      xxd -g 1 user/usr/bin/hello.exec

  Useful GDB commands:

      add-symbol-file user/usr/bin/hello.exec 0x08048094
      b __libc_static_entry
      b main
      b *0x12345678
      layout asm
      layout next
      si
      info registers
      kernel info vmmap_mapping_info curproc->p_vmmap

• Week 13 (TXT) - fork(), user space shell

  Code (user):

  • fork-and-wait.c
  • /sbin/init.c

  
  Kernel 3 FAQ:

  • do_fork()
  • "/sbin/init" not working

  Remaining user space programs:

  Code (user):

  • memtest.c
  • eatmem.c
  • forkbomb.c

  
  Kernel 3 FAQ:

  • dynamic region and do_brk()
  • make forkbomb run forever

• Week 14 - (no discussion section this week)
• Week 15 - (no discussion section this week)