x86OS

x86OS is an x86-based hobby opearting system.

This project was originally started in around 2002 or 2003 and then abandoned for a long time. I resurrected it in around 2019 and got it building again on modern systems.

It is booted using a GRUB multiboot boot sector (this part wasn't written by me) on a floppy disk image.

It is primarily designed to be run using VirtualBox.

These things work in a "held together by duct tape" kind of way:

• Keyboard input and console output
• Readonly FAT12 floppy driver
• Serial port driver for debug output
• Preemptive multitasking with a simple scheduler
• Basic sleep timer support
• A tiny subset of POSIX syscalls (read, write, open, stat, posix_spawn, etc.)
• Loading and executing user-mode ELF binaries
• The beginnings of a standard I/O layer
• The beginnings of a set of user-mode utilities like ls, ps, and so on
• The beginnings of a ProcFS (/proc)

These things do not exist yet:

• Proper memory management
• Writable filesystems
• A proper VFS layer
• Support for networking, sound, usb, video, hard disks, etc.
• Literally everything else

Development

Building and Running

The build environment is dockerized:

• make docker-init
  • This will build the base docker image
• make docker-build
  • This will compile x86os and produce a bootable floppy image in the root directory called ./floppy.img
• make run-qemu
  • Launches x86os in QEMU using the floppy image. Requires qemu-system-i386.
• make run-virtualbox
  • Launches x86os in VirtualBox. Requires VirtualBox and a VirtualBox VM called x86os.

If you don't want to use the dockerized version you'll need these tools installed:

• GCC
• NASM
• A version of LD that supports linker scripts, such as LLVM's ldd. The default ld in OS X does not support them.
• mtools for manipulating the floppy image