Build a minimal multi-tasking OS kernel for ARM from scratch

Prerequisites

• QEMU with an STM32 microcontroller implementation
  • Build instructions

./configure --disable-werror --enable-debug \
    --target-list="arm-softmmu" \
    --extra-cflags=-DSTM32_UART_NO_BAUD_DELAY \
    --extra-cflags=-DSTM32_UART_ENABLE_OVERRUN \
    --disable-gtk
make

• GNU Toolchain for ARM
• Set $PATH accordingly

Steps

• 00-HelloWorld
  • Enable STM32 USART to print trivial greetings
• 01-HelloWorld
  • Almost identical to the previous one but improved startup routines
• 02-ContextSwitch-1
  • Basic switch between user and kernel mode
• 03-ContextSwitch-2
  • system call is introduced as an effective method to return to kernel
• 04-Multitasking
  • Two user tasks are interatively switching
• 05-TimerInterrupt
  • Enable SysTick for future scheduler implementation
• 06-Preemptive
  • Basic preemptive scheduling

Building and Verification

• Changes the current working directory to the specified one and then

make
make qemu

Licensing

mini-arm-os is freely redistributable under the two-clause BSD License. Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.

Reference

• Baking Pi – Operating Systems Development