🖥️ MyOwn64XOS — A Simple 64-bit Operating System Kernel

🧩 Introduction

MyOwn64XOS is a simple 64-bit kernel developed in C and Assembly.
It demonstrates fundamental operating system concepts such as bootloading, memory paging, long mode transition, and basic VGA output.

Upon startup, the kernel clears the screen, displays a welcome message, and prints a stylized NUST text banner using ASCII characters.

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🚀 Features

• ✅ Multiboot2-Compatible Bootloader for GRUB
• ✅ Transition from 32-bit Protected Mode → 64-bit Long Mode
• ✅ Page Table Setup using 2 MiB huge pages
• ✅ Basic VGA Text Output (0xb8000)
• ✅ Custom Print Functions for strings, newlines, and colors
• ✅ ASCII Art Rendering of “NUST”
• ✅ Clean, modular structure separating C and Assembly logic

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🧱 Project Structure

MyOwn64XOS/ │

├── kernel.c # Kernel entry point (kernel_main)

├── boot.asm # Bootloader and CPU checks

├── long_mode.asm # 64-bit mode setup and GDT

├── print.c / print.h # VGA text output functions

├── linker.ld # Linker script

└── Makefile # Build and run commands

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⚙️ How It Works

1. Bootloader Stage

• Initializes stack and verifies CPU compatibility (CPUID, Long Mode support)
• Prepares GDT and memory paging
• Jumps to 64-bit long mode

2. Memory Paging

• Sets up page tables (L4 → L3 → L2)
• Maps memory using 2 MiB huge pages

3. Kernel Initialization

• Clears VGA text screen

• Sets text color

• Displays:

• Renders ASCII “NUST” pattern

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🧠 Technologies Used

• C – for kernel logic and output functions
• x86-64 Assembly – for bootloader and low-level setup
• QEMU – emulator for testing
• GRUB – Multiboot2-compliant bootloader

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🧪 Build and Run Instructions

🔧 Requirements

• gcc (cross-compiler for i686-elf)
• nasm
• qemu-system-x86_64
• make
• grub-mkrescue

🛠️ Steps

# Clone repository
git clone https://github.com/yourusername/MyOwn64XOS.git
cd MyOwn64XOS

# Build kernel
make

# Create bootable ISO
make iso

# Run in QEMU
qemu-system-x86_64 -cdrom MyOwn64XOS.iso

🖥️ Example Output

-------------------------------------------------
Welcome to our 64-bit kernel!
-------------------------------------------------

 Printing NUST Text Using Asterisks :

*****         ***   ****          ****   *************   *************
** ***        ***   ****          ****   *************   *************
**   ***      ***   ****          ****   *****              *****
**     ***    ***   ****          ****   ****               *****
**       ***  ***   ****          ****   *************      *****
**        *** ***   ****          ****            *****     *****
**          *****   ****          ****            *****     *****
**           ****   ******************   **************     *****
**           ****   ******************   **************     *****

🎯 Learning Outcomes

In-depth understanding of x86_64 architecture

Practical experience with paging and GDT setup

Hands-on practice with VGA text buffer manipulation

Integrating C and Assembly for OS development

👩‍💻 Contributors

Urooj Fatima Raza (Developer & Author of MyOwn64XOS)

🌟 Acknowledgment

Developed as part of an Operating Systems project to demonstrate the fundamentals of 64-bit kernel design at NUST.