OH-WES

OH-WES is an OS for Wes! Written by me for the sole purpose of learning about operating systems the hard way (also because I find this sort of thing fun). OH-WES is a 32-bit protected-mode operating system for the Intel 386 and is currently in early development.

What does it do?

Not much yet, on the surface anyways. It features a somewhat VT100-compatible text terminal with working keyboard input. Currently, it runs in ring 3 Protected Mode in a crude userland baked into the kernel image (no program loader yet). It can talk to the kernel through a system call interface and features the usual read/write/open/close/ioctl driver framework. Right now, the RTC and console are the the only supported devices. :-) It runs on real hardware (tested on three different PCs from 1997-2004, at least) and can theoretically run on any PC with an Intel 386 processor (tested with various PCem emulations).

Things I still need to do before it's really a working OS are: create a floppy disk driver and program loader, implement basic filesystem support (FAT-12 at first, maybe ext2 later), enable virtual memory and build a dynamic memory allocator, allow for terminal switching, and create a program scheduler. Eventually I'd like to try hooking up a a real serial terminal and see if I can interact with the system over the serial I/O port, as well as play with the GPU and attempt to implement a 3D graphics driver. Maybe even port DOOM or GTA3? :-)

How do I use it?

Clone the repo

> git clone --recurse-submodules https://github.com/whampson/ohwes

Prepare the Environment

Install GCC Cross Compiler

Install a GCC cross-compiler. This will be used to build the operating system code. Currently, we are using GCC 7.1.0 graciously pre-compiled by lordmilko at lordmilko/i386-elf-tools:

1. Download i686-elf-tools-windows.zip or i686-elf-tools-linux.zip.
2. Extract .zip contents to build/i686-elf-tools/
   • Your build directory structure should look like this:

     ohwes/
     └───build/
         └───i686-elf-tools/
             ├───bin/
             ├───include/
             ├───lib/
             ├───libexec/
             └───share/
     

Install Native Build Tools (Windows)

OH-WES is built on Windows under a MINGW32 environment using a GNU Make and GCC.

1. Install MSYS2 and QEMU.

PS> winget install msys2
PS> winget install qemu

If you do not have winget, see Windows Package Manager for Developers.

2. Update MSYS2. You will need to run this command again if you are prompted to restart the shell.

MSYS2> pacman -Syuu

3. Install native build tools.

MSYS2> pacman -Syu msys/make
MSYS2> pacman -Syu mingw32/mingw-w64-i686-toolchain

4. Use a MINGW32 shell to build OH-WES (see Building OH-WES).

Install Native Build Tools (Linux/Debian)

1. Install build-essential

> apt-get install build-essential

Build OH-WES

Open a Bash shell (MINGW32 on Windows) and navigate to the project root, then source the environment script. This script will ensure your PATH is set correctly and that the necessary tools are accessible (this only needs to be done once per session).

> cd ohwes/
> . scripts/env.sh

Now, simply run make to begin building OH-WES!

> make

Run OH-WES with QEMU or Bochs

To run with QEMU, install QEMU and make sure qemu-system-i386 is in your path, then:

> make run

For Bochs, just install Bochs and make sure bochs is in your path, create a bochsrc.bxrc file and put it in the project root, then:

> make run-bochs

Create an OH-WES Floppy Disk Image

You can create a floppy disk image of OH-WES by running the following:

> make img

This builds my fatfs tool then creates a FAT-12 floppy disk image using it. You can point other emulators to this image, or write it to a real floppy disk via the dd command.

Create a Bootable OH-WES Floppy Disk 💾

You may also bypass creating an image and write the files directly to disk if your system has FAT-12 support:

> make format-floppy         # DESTROYS ALL DISK CONTENTS
> make floppy                # assumes disk is mounted at /a/

The format-floppy command only needs to be run if the disk is not FAT-12 formatted or if the kernel size changes considerably, as the bootloader does not support fragmentation. If you experience weird glitches while using a real floppy disk , try formatting the disk first. Then again, it may be bugs in my code... :-) have fun!