OS

Quick Start

# clone the repo
git clone git@github.com:jbw3/OS.git
cd OS

# install dependencies
sudo apt install -y nasm xorriso grub-pc-bin
./tools/build-gcc.py

# build OS (as ISO image)
make release iso

# run in QEMU
qemu-system-i386 -cdrom bin/OS-x86.iso

Requirements

Building the Cross-Compiler

To build the OS kernel you will need a cross-compiler. GCC 7.2.0 is the compiler currently being used. Some other compilers or GCC versions will probably work, but note that support for the C11 and C++17 standards is required. A script to build a GCC cross-compiler can be found in the tools directory: build-gcc.py. A tutorial can also be found at OSDev. Run build-gcc.py -h for help and command line options.

Assembler

This project uses the NASM assembler. On Ubuntu, it can be installed as follows:

sudo apt install nasm

Building

To build the OS kernel, run make in the top-level directory. A GRUB-bootable ISO image can also be created by running make iso. Both the kernel binary and ISO image will be placed in the bin directory.

Note: The xorriso and grub-pc-bin packages may be needed to create the ISO image. On Ubuntu, they can be installed as follows:

sudo apt install xorriso
sudo apt install grub-pc-bin

Running

QEMU

Use the following command to run the OS in QEMU:

qemu-system-i386 -cdrom bin/OS-x86.iso

The -serial stdio option may also be added to redirect a serial port to the terminal. The OS runs a shell with IO redirected to this serial port giving you an OS shell in your terminal:

qemu-system-i386 -serial stdio -cdrom bin/OS-x86.iso

Bare Metal

The ISO image can be copied to a USB drive using the following command replacing sdx with the USB drive:

sudo dd if=bin/OS-x86.iso of=/dev/sdx

IMPORTANT: The dd command will wipe the contents of your USB drive. Also, if you accidentally point it to another drive (say, your hard drive), it may wipe that too!

Shell

The OS has a simple shell for debugging purposes. Type help to list the available commands.