README.md

FrOS

Description

This is a simple x86 32 bit operating system written from scratch, based on Carlos Fenollosas OS tutorial. It contains the following components:

1. Boot loader
2. Operating system kernel, including
   1. ISRs to handle CPU interrupts
   2. VGA driver
   3. Keyboard driver
   4. Shell
   5. Dynamic memory allocation

Setup

Install Assembler and Emulator

brew install qemu nasm

Install Kernel Compiler

https://github.com/lordmilko/i686-elf-tools#mac-os-x

brew install i386-elf-binutils
brew install i386-elf-gcc
brew install i386-elf-gdb

export PATH="/usr/local/Cellar/x86_64-elf-binutils/<version>/bin/:/usr/local/Cellar/x86_64-elf-gcc/<version>/bin/:/usr/local/Cellar/i386-elf-gdb/<version>/bin:$PATH"

Usage

Boot

make run

Debug

make debug

In GDB shell:

• Set breakpoint at function (e.g. start_kernel): b start_kernel
• Start execution: c
• Jump to next instruction: n
• Print variable: p <variable_name>

Additional Resources

• Writing a Simple Operating System — from Scratch
• OS Dev Wiki
• JamesM's Kernel Development Tutorials
• BrokenThorn Entertainment's Operating System Development Series
• The Little Book About OS Development
• C Memory Allocation Functions