ChariotOS

Chariot is a simple unix-like kernel and userspace designed to easily play around in if you are interested in kernel development. It currently supports x86 and RISC-V, and "compiles" for ARM64 (help wanted). It's written in C++ and, with the exception of a few ports for my sanity, is entirely contained in this repo.

If you are interested in helping out with development, feel free to file a PR! I'd love all the help I can get.

Building

Building the kernel currently has quite a number of host dependencies. A (likely incomplete) list follows:

cmake
make
ninja
python3
nasm
grub2

On ubuntu, you can install the prereqs using:

sudo apt install -y
build-essential manpages-dev
cmake ninja-build
libtool-bin
gettext
python3
python3-pip
python3-venv
makeinfo
texinfo
libgmp-dev
libmpfr-dev
libmpc-dev

Once you have those, building the kernel from scratch takes a few steps (subsequent builds are little more than make).

First, you need to configure the kernel. Let's assume building for x86, just run the command make menuconfig and exit. That will configure the kernel with the default, sane configuration.

Once you do that, you will need to build a toolchain.

$ cd toolchain
$ ./build.sh x86_64

This command will build binutils and gcc for cross compilation. If you want to build for RISC-V, replace "x86_64" in the build command with riscv64.

Once you have that built, go back to the root of the project and build some of the required ports (freetype):

$ cd ports
$ ./build.sh x86_64
$ cd ../

Now, you can build the kernel. make will build it to build/chariot.elf, and you can run tools/sync.sh to create a bootable disk image at build/chariot.img. You can of course run the kernel in QEMU with tools/run.sh. All additional options to this script are passed through to QEMU, so I typically run with tools/run.sh -nographic when doing development.

Feel free to file any issues if anything doesn't work!