ZenOS

[Note: This is still very much a work in progreess with a long way to go]

ZenOS is a minimal educational operating system built from scratch for the x86_64 architecture. The goal of this project is to understand how an operating system works at the lowest level including but not limited to:

• booting
• memory management
• interrupts
• multitasking
• user/kernel separation.

This OS is built using C and x86 assembly, runs on bare metal, and is tested using QEMU.

Tooling

• Emulator: QEMU (x86_64)
• Compiler: Cross-compiled GCC (x86_64-elf)
• Bootloader: GRUB (Multiboot2)

Build Requirements

The following tools are required on the host system:

• GNU Make
• GCC and Binutils
• GRUB
• xorriso
• GDB
• QEMU

Directory Structure

zen-os/
├── README.md
├── .gitignore
├── src/      # kernel C code
├── arch/x86_64/   # architecture-specific code (ASM, linker)
├── build/     # build artifacts
└── scripts/     # helper scripts

Cross-compiler dependencies

• gmp
• mpfr
• libmpc

Roadmap

• Cross-compiler toolchain
• Bare-metal kernel entry
• VGA text output
• Memory management
• Interrupt handling
• Scheduler
• User mode support
• File system

Cross-Compiler Toolchain

A freestanding x86_64-elf cross-compiler is used to ensure the kernel does not depend on the host operating system. Components:

• binutils (assembler and linker)
• GCC (C compiler without standard library) The GCC build is configured as freestanding:
• No libc
• No system calls
• No host OS dependencies

Building the Toolchain

The cross-compiler toolchain is not stored in the repository. To build it locally run:

./scripts/build-toolchain.sh

This will download, build, and install a freestanding x86_64-elf GCC toolchain under toolchain/install/.