Os Chan

Os Chan is a staged x86_64 hobby kernel built on Limine.

The project validates progress with deterministic headless QEMU logs (oschan: ... tokens) and a smoke harness.

Output Model (Important)

• Kernel milestone logs are written to QEMU debugcon (isa-debugcon at I/O port 0xE9).
• The primary verification flow is headless (make qemu-headless and make test-smoke).
• make run uses VNC output. A blank VNC window is expected because the kernel does not currently render framebuffer text.

Dependencies

• GNU make (make on Linux, gmake on non-GNU systems)
• C toolchain for x86_64 freestanding kernel build (gcc/binutils or clang/llvm/lld)
• xorriso (ISO creation)
• python3 (initramfs generation via scripts/mkinitramfs.py)
• qemu-system-x86_64 (run targets)
• timeout (smoke harness)
• Optional:
  • gdb (for make qemu-gdb attach)
  • curl, tar, gunzip (UEFI firmware fetch via make edk2-ovmf)
  • sgdisk, mtools (HDD image targets)

Toolchain Selection

The kernel build supports TOOLCHAIN and TOOLCHAIN_PREFIX.

Examples:

make TOOLCHAIN=llvm
make TOOLCHAIN_PREFIX=x86_64-elf-

Common Targets

• make or make all
  • Build bootable ISO at dist/os-chan.iso.
• make iso
  • Alias for ISO build.
• make qemu-headless
  • BIOS headless run with debugcon output to stdout.
• make qemu-headless-uefi
  • UEFI headless run with OVMF (make edk2-ovmf done automatically by dependency).
• make qemu-gdb
  • Headless run paused with gdbstub on :1234 (-S -gdb tcp::1234).
• make test-smoke
  • Run headless smoke verification and assert required oschan: tokens.
• make run
  • Interactive VNC run (-vnc :0). Useful for bootloader visibility; kernel logs are still debugcon-based.
• make run-uefi
  • Interactive UEFI run.
• make all-hdd, make run-hdd, make run-hdd-uefi
  • HDD image build/run variants.

Quick Start

make iso
make qemu-headless
make test-smoke

GDB Quick Attach

In terminal 1:

make qemu-gdb

In terminal 2:

gdb -q -ex "target remote :1234" -ex "info registers"

Notes

• Avoid running multiple ISO/QEMU make targets in parallel. They share temporary iso_root/ and can race.
• Reference background reading: https://osdev.wiki/wiki/Limine_Bare_Bones