HellOS

HellOS stands for "Hello, OS!". As its name suggests, it is an OS for learning and practice.

Getting Started

Environment

• Shell: Bash on Linux/WSL or MSYS2/MinGW on Windows
• Assemble: NASM
• C Compile: OpenWatcom (16-bit), GCC(32-bit)
• Disk Tools: fdisk (from util-linux), mkfs.fat (from dosfstools), mcopy(from mtools)
• VM: QEMU

Steps

1. Go to a target directory (e.g. src/boot/hello).
2. Run build.sh, or make if makefile exists. This will assemble the .asm files and compile any .c files, producing the necessary binary files (.bin, etc.).
3. Run mkdisk.sh if exists, or make disk if makefile exists. This will create the virtual disk images (.img files) needed for booting.
4. Run run.sh or make run if makefile exists. This will start QEMU and boot the target Bootloader/OS.

Example using src/boot/hello:

cd src/boot/hello
./build.sh
./run.sh

Roadmap

• Bootloader (MBR)
  • ✓ Print Hello
  • ✓ Interactive Console (Echo, shutdown, reboot)
  • ✓ Two-stage loader
    • ✓ FAT driver (Read Only & Root Dir Only)
      • ✓ FAT 12
      • ✓ FAT 16
      • ✓ FAT 32
    • ✓ Load kernel file
    • ✓ Interactive Console
• 16-bit Real Mode:
  • ✓ Hello in C Language
  • ✓ Interactive Console in C Language
    • ✓ Override VGA Text Mode Driver (Replace int 10h)
    • ✓ Override PS/2 Keyboard Driver (Replace int 16h)
    • ✓ Override System & Power Services (Replace int 15h/19h)
  • File System Commands (cat, echo >, touch, ls, cd, mkdir, rmdir, rm, cp, mv)
    • Override Disk Driver (Replace int 13h)
    • FAT Driver (Read & Write)
  • External Command
    • Execute Flat Binary From Disk
    • Provide stdio.h — Run Classic C Exercises (printf, puts, file I/O)
    • Provide dos.h — Porting Tank War, My University C Course Project
• 16-bit Protected Mode
  • Hello in Ring 3
    • IO Interrupts
    • Memory Management
    • Process Context (Single Process)
    • Protected Mode API
  • Interactive Console in Ring 3
  • File System Commands in Ring 3
  • External Command in Ring 3
• 32-bit Protected Mode
  • Hello (32-bit)
    • Process with Memory Paging
  • Interactive Console (32-bit)
  • File System Commands (32-bit)
    • Cooperative Multitasking
    • Preemptive Multitasking
• 64-bit Long Mode
  • Hello (64-bit)
  • Interactive Console (64-bit)
  • File System Commands (64-bit)
  • External Command (64-bit)
  • UEFI Support