CS 452/652 Winter 2026 - Lecture 1

Introduction and Overview

Jan 6, 2026 next

Course Overview

• real-time systems
  • software that interacts with the real world
  • model/control physical world, communication, timing
  • robustness against defects (train, switch, sensor)
• real-time systems
  • small operating system, plus train control application
  • start from scratch, get a better understanding of things you may take for granted
    • limited memory translation/protection, no file system
    • micro-kernel with send-receive-reply (SRR) communication
    • multi-threading; concurrency & non-determinism
    • device interaction; interrupt handling
• few guard rails; room to roam
  • design flexibility in assignments
  • you define and implement a project

Infrastructure

RPi Boot Process

• bootloader loads start4.elf and other files (config.txt)
• bootstraps VideoCore (VC) GPU and loads kernel8.img
• jumps to 0x80000 to hand control to kernel
• VideoCore does other things behind the scenes

Development Overview

• basic procedure
  1. build and create .img file on dev box
  2. upload .img to boot server (cs452.student.cs.private.uwaterloo.ca)
  3. reboot / power on RPi (output to gtkterm on test PC)
  4. RPi automatically loads image for its MAC address
• dev PC: use wireshark (interface can0) to observe raw CAN bus traffic

Sample Code

• iotest
  • very simple, does console input/output using serial link
  • checks for incoming CAN bus frames
  • MMU set up for basic identity mapping: split at 0x200000: details later
  • use it to try the dev/test process
• development tools
  • cross-compiler and other usual tools (linker, readelf, etc)
  • on linux.student.cs.uwaterloo.ca, tools are in /u/cs452/public/xdev/bin
  • on personal computer, install your own (see course web page)

Development Basics

• freestanding code
  • no operating system, no libraries
  • explicit linking rules
  • standard libraries (C, C++) permitted, but require extra work
• libc (newlib) is part of compiler package, but no system calls
  • cannot rely on underlying OS to provide services, like I/O, memory allocation

Assignment 0

• due in two weeks! start now!
• polling loop, checking track state, clock, user input

  for (;;) {
    if (c1) f1();
    if (c2) f2();
    ...
  }
  

Important Notes

• please be careful in the lab and very careful with the trains & track
• please do not place anything (bachpacks, etc) on the tracks/desks, including the older tracks
• please clean up garbage