# OS3

Hobby bootable software suite for x86 (NOT x86_64) systems.

## Building

This repository needs 2 separate compilers to function:

 - a generic C/C++ compiler for the "host" (whatever architecture that may be)
 - a i686-elf GCC/Binutils cross-compiler accessible in the path (i686-elf-gcc, i686-elf-objcopy, etc...)

It also needs mkfs.vfat (or newfs_msdod on macOS).

The build system is cmake.

First, generate the host utilities:

    cmake -S host -B build/host
    cmake --build build/host

Then, generate the bootable image:

    cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=CMakeToolchain.txt
    cmake --build build

The image might run (the `main` branch is not a stable one) via qemu and the following command:

    qemu-system-i386 --hda build/kernel.img

## Components

In order of dependency:

### libfat

Library for handling FAT32 file systems. Can be built for both kernel or host.

### os3_common

Common headers shared between host tools and kernel code.

### host

A collection of host tools required to build the bootable image

### mbr

Stands for "Master Boot Record". It's an assembly file designed to be bootable from MBR x86 systems. (EFI Incompatible).

### stage1

Stage 1 bootloader. Written in C. Should initialize most required drivers (USB, Disks, ACPI, Video). Currently not done.

### rawimg

Disk image. It's built in multiple stages via various host tools.