π§ Roadmap to Build Your Own Operating System (OS)
Creating your own OS is a challenging but highly rewarding project. This guide is designed to take you from zero to a basic functional OS step-by-step.
π§ Overview of OS Development Phasesβ
π’ Phase 1: Preparation & Fundamentalsβ
π― Goal: Understand how an OS works and set up your environment.
- Learn C (deep dive) and Assembly (x86 basics).
- Understand boot process: BIOS β Bootloader β Kernel.
- Learn basic computer architecture (x86/x86_64 or ARM).
Resources:
- π The Little Book About OS Development
- π βOperating Systems: Three Easy Piecesβ (OSTEP Book)
π οΈ Phase 2: Setup Environmentβ
π― Goal: Prepare your development and testing environment.
- Install essential tools:
GCC
orClang
NASM
orGAS
QEMU
orBochs
GRUB
bootloader
Project Structure:
/myos/
βββ bootloader/
βββ kernel/
βββ Makefile
π Phase 3: Bootloaderβ
- π― Goal: Create a bootloader to load your kernel.
- Write 16-bit real mode boot sector in Assembly.
- Transition to protected mode or use GRUB to load the kernel.
boot.asm
[bits 16]
org 0x7c00
jmp start
start:
mov ah, 0x0E
mov al, 'H'
int 0x10
jmp $
times 510 - ($ - $$) db 0
dw 0xAA55
π§ Phase 4: Kernel Development (C + ASM)β
π― Goal: Write a simple kernel with a C entry point.
- Switch to Protected Mode
- Setup GDT (Global Descriptor Table)
- Setup IDT (Interrupt Descriptor Table)
- Handle keyboard & timer interrupts
- Add a kernel_main() function
void kernel_main() {
printf("Welcome to MyOS!");
while(1);
}
π§© Phase 5: Core Kernel Featuresβ
π― Goal: Implement key OS functionalities.
- β Memory Management (Physical/Virtual, Paging, Heap)
- β FileSystem Support (FAT32, EXT2)
- β Drivers (Keyboard, Display, Disk)
- β Interrupts & System Calls
- β Process Scheduler & Multitasking
- β Basic Shell or TUI (optional)
π§βπ» Phase 6: User Space & Applicationsβ
π― Goal: Create a basic CLI with user programs.
- Setup system call interface
- Implement ELF binary loader
- Create shell, calculator, etc.
π Phase 7: Advanced Features (Optional)β
π― Goal: Take your OS to the next level.
- Build Networking Stack (TCP/IP)
- Create GUI with VESA/Framebuffer
- Add USB, PCIe drivers
- Multi-core CPU support
π Example Project Folder Structureβ
/myos
βββ bootloader/
β βββ boot.asm
βββ kernel/
β βββ kernel.c
β βββ memory.c
β βββ scheduler.c
βββ drivers/
β βββ keyboard.c
β βββ video.c
βββ include/
β βββ kernel.h
βββ lib/
β βββ stdio.c
βββ Makefile
π§° Recommended Toolsβ
- Tool Purpose
- NASM Assembly code
- GCC/Clang Compiling kernel (C)
- QEMU Emulator for testing
- GDB Debugger
- GRUB Bootloader
- Make/CMake Build system