CaCOS

*Coherent and Cohesive Operating System*

CaCOS (k-a-k-o-s) is a simple hobby operating system. It's goal is to be functional and have a clean and elegant codebase, as much as possible. In the current rewrite there is a text console, a basic file system, and userland applications. You can see how the operating system is designed in the docs

---

The Plan

Here are all the steps of the development of the os.

Boot loader

implement the bootboot boot protocol

automate bootboot installation and image creation

Core functionality

frame-buffer

basic functions

text display

memory

page allocation and tracking

memory freeing

system
interrupt descriptor table (IDT) setup
global descriptor table (GDT) setup
interrupt service routine (ISR) setup

advanced functionality

Keyboard driver

Filesystem

basic ramfs and file structures

basic filesystem functions (create, delete, read, ...)

path handling

filesystem on disk

Elf file loading

parse elf file

load and execute elf file

system calls

call kernel code from apps

pass arguments and return errors

error marshalling, through kernel and apps

console

execute commands

standard text streams

apps

write simple apps leveraging elf loading and system calls

write a standard library providing basic functionality (memory, filesystem, ...)

build a complete set of utils, akin to busybox (filesystem utils, text manipulation, ...)

Beyond

threads and multi tasking

write a scheduler

context switches and multitasking

multi threading

PCI driver

support for hardware accelerated graphics

mouse driver and support

complete graphical interface

networking

porting linux binaries and utils

Running the OS

NOTE: the OS is currently in heavy development and the process to run the OS is not streamlined yet

NOTE: running on macos or windows has never been tested, though it should work fine

To run the CacOS you have to download the most recent image from the releases tab, and then run the following command: qemu-system-x86_64 -drive format=raw,file=kernel/img/cacos.img

Alternatively, you can clone the git directory (git clone https://github.com/kanajakala/cacos.git CaCOS), cd into it (cd CaCOS) and then run (zig build run --release=small)

currently there is not much you can do, you can type motd to show the motd, or ls <dir> to show the files in the provided directory

Building the OS

you will need the following dependencies:

• zig 15 for compiling the project
• qemu-system-x86_6 to run the os
• git to clone the git repository
• zip for building bootboot (done automatically)

running the following command will download and compile bootboot, and it's image utility "mkbootimg", compile the OS code for you and run it in qemu:
zig build run

you can customize the build process by running specific steps:

• zig build compile generate an elf executable of the kernel
• zig build compile-apps generate executables for the kernel apps
• zig build setup dowloads and build mkbootimg, bootboots utility program to generate bootable images
• zig build gen create a bootable image using mkbootimg
• zig build run run the all the previous steps, and run the image in qemu