what has

memory - paging, heap allocator, placement allocator for early boot

filesystem - unified VFS, ramdisk, FAT16

networking - RTL8139 driver, ARP, IP, ICMP, UDP, DHCP

9P server - kernel VFS exposed over 9P2000/UDP on port 9999; host can mount and read/write it

multitasking - preemptive round-robin scheduler, semaphores

prolog repl - embedded trilog interpreter with FFI; with some predicates to interact with the system

display - 80×25 text mode, VGA 640×480 16-color, BDF font rendering

building

locally

apt install build-essential nasm qemu-system-x86 gdb clang-format tcpdump dnsmasq bridge-utils iproute2 net-tools procps mtools dosfstools
git clone --recurse-submodules <repo>
make

docker

# build the docker container
docker build -t os-dev .

# run the container
sudo docker run -it --privileged --cap-add=NET_ADMIN \
    -v $(pwd):/workspace \
    -p 5901:5901 \
    os-dev bash

# setup the network inside the container
bash tools/dhcp.sh

# build and run emulation
make vnc

# attach from the outside
vncviewer localhost:5901

vfs over 9p

The kernel exposes its VFS over 9P2000 on UDP port 9999. tools/c9 contains a C bridge and SWI-Prolog client library for talking to it from the host.

# build the os-dev image first (if not already done)
docker build -t os-dev .

# start the kernel, bridge, and a treewalk of the VFS
docker compose -f tools/c9/docker-compose.yml up

The treewalk walks the entire VFS and prints the directory tree:

connected - walking /

d  fd  (0 bytes)
  -  CORE.PL  (1387 bytes)
  d  FONTS  (0 bytes)
      -  VIII.BDF  (19389 bytes)
      -  tom-thumb.bdf  (19864 bytes)
d  ramdisk  (0 bytes)

See tools/c9/prolog/p9.pl for the Prolog API (connect/4, ls/3, read_file/3, write_file/3, stat/3).