A simple, educational operating system with a C++ kernel targeting x86 architecture.
FoxOS is a hobby operating system built from scratch in C++ for learning low-level systems programming. It implements core OS concepts including memory management, interrupt handling, and hardware drivers while maintaining a clean, modular architecture. The project serves as a practical exploration of operating system fundamentals—from bootloader to userspace—with readable, well-structured code.
- x86 32-bit Protected Mode — Runs in protected mode with Multiboot-compliant bootloader
- Memory Segmentation — GDT with Ring 0 (kernel) and Ring 3 (user) privilege levels
- Interrupt Handling — Full IDT with 256 interrupt/exception handlers and PIC remapping
- Virtual Memory — Paging with 4KB pages (1024 entries per table, 1024 tables per directory)
- Page Fault Handling — Dynamic frame allocation and deallocation
- Kernel Heap — malloc/free implementation with expandable heap (up to 16MB)
- Keyboard Driver — Full keyboard input with EN-US and Dvorak layouts
- VGA Terminal — 80×25 text mode display with color support
- System Timer — Programmable Interval Timer (PIT) for system clock
- Custom Operators — Kernel-specific
new/deleteimplementations - Standard Library — Freestanding libc and libc++ (stdio, string, memory, collections)
- Global Constructors — Full C++ static initialization support
| Directory | Purpose |
|---|---|
kernel/ |
Core kernel implementation |
kernel/arch/i386/ |
x86-specific code (boot, GDT, IDT, paging, drivers) |
kernel/kernel/ |
Main entry point (kernel.cpp) |
kernel/include/ |
Public kernel headers |
libc/ |
Freestanding C standard library |
libc++/ |
C++ standard library (memory, collections, I/O) |
| Component | File | Description |
|---|---|---|
| Boot | boot.asm |
Multiboot entry point, stack setup |
| GDT Manager | GdtManager.cpp |
Memory segmentation, privilege rings |
| IDT Manager | InterruptManager.cpp |
Interrupt/exception handling |
| Paging Manager | PagingManager.cpp |
Virtual memory, 4KB pages |
| Memory Heap | MemoryHeap.cpp |
Kernel malloc/free |
| Keyboard Driver | KeyboardDriver.cpp |
Keyboard input (US, Dvorak) |
| TTY Manager | TtyManager.cpp |
VGA text mode output |
| Timer Manager | TimerManager.cpp |
System clock (PIT) |
| Script | Purpose |
|---|---|
config.sh |
Build environment configuration |
headers.sh |
Install headers to sysroot |
build.sh |
Compile kernel and libraries |
iso.sh |
Create bootable ISO |
qemu.sh |
Launch in QEMU emulator |
The kernel uses a modular manager-based architecture:
- GRUB loads the kernel via Multiboot
- KernelManager orchestrates all subsystems
- Core managers (GDT, IDT, Paging) handle CPU/memory setup
- Hardware drivers (Keyboard, Timer, TTY) interface with devices
- libc/libc++ provide runtime support
# Install Homebrew (if not already installed)
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
# Install build dependencies
brew install make
brew install gmp mpfr libmpc
brew install xorriso
brew install qemu
# Install i686-elf cross-compiler toolchain
brew install i686-elf-gcc
# Install GRUB for creating bootable images
# See: https://wiki.osdev.org/GRUB
#Installing_GRUB_2_on_OS_X
Linux (Debian/Ubuntu)
sudo apt update
sudo apt install build-essential bison flex libgmp-dev libmpc-dev libmpfr-dev texinfo
sudo apt install xorriso grub-pc-bin qemu-system-x86
# Build cross-compiler toolchain
# See: https://wiki.osdev.org/GCC_Cross-Compiler
Building
# Clone the repository
git clone https://github.com/TeddyEngel/FoxOS.git
cd FoxOS
# Configure build environment (edit config.sh if needed)
./config.sh
# Install headers
./headers.sh
# Build the kernel and libraries
./build.sh
# Create bootable ISO
./iso.sh
Running
QEMU (Recommended)
# Build and run in one step
./build_and_run.sh
# Or run manually after building
./qemu.sh
Bochs
# Edit bochsrc.txt to configure Bochs settings
./bochs.sh
VirtualBox / VMware
1. Build the ISO with ./iso.sh
2. Create a new VM (Other/Unknown 32-bit)
3. Allocate at least 32MB RAM
4. Mount FoxOS.iso as the CD/DVD drive
5. Boot the VM
Contributing
Contributions are welcome! Feel free to:
- Report bugs or suggest features via Issues (https://github.com/TeddyEngel/FoxOS/issues)
- Submit pull requests for improvements
- Improve documentation
Resources
- OSDev Wiki (https://wiki.osdev.org/) — Comprehensive OS development resource
- Intel Software Developer Manuals (https://www.intel.com/content/www/us/en/developer/articles/technical/intel-sdm.html) — x86 architecture reference
- James Molloy's Kernel Tutorial (http://www.jamesmolloy.co.uk/tutorial_html/) — Classic kernel development guide
License
This project is licensed under the BSD 2-Clause License. See LICENCE (LICENCE) for details.
*Built with curiosity and caffeine*