dreamos82/northport

Osdev round 2! Monolithic kernel design, and targetting x86_64. Check the readme for more details.

Northport is a monolithic kernel, written in C++ and booted via the Limine protocol. It currently supports x86_64 and riscv64 machines. This repo also contains a completely standalone support library (see libs/np-syslib).

Instructions for building it yourself are available here, and a more in-depth manual can be found under the releases tab or by cloning this repository and running make docs.

A brief summary of the current goals and features are listed below, or check the roadmap for a more granular view. Pre-built isos are made available at major feature milestones, but for the latest and greatest it's recommended to build from the master branch.

Project Goals

1. To build a usable, extensible and relatively complete kernel. This means an smp-aware scheduler with support for heterogeneous processors, media stacks (graphics, audio and network) and a flexible driver infrastructure.
2. Support for multiple architectures: the current targets are x86_64 and riscv64, but this may expand over time.
3. Be self hosting, this includes cross compiling the system.
4. Clean code and useful documentation.
5. Usable on both virtual machines and real hardware.

An extended goal (previously goal #5) is to add a comfortable user experience: a window manager, basic programs like a text editor and file explorer.

Project Features

Kernel:

• Support for multiple architectures: riscv64, x86_64.
• Memory management:
  • PMM with a fast path for single page allocations (freelist), and a slow path for allocations with imposed limits (required by some drivers).
  • Modular and portable VMM, with demand paging options for anon and vfs backed memory. Inspired by the old SunOS design.
  • General purpose heap provided by slabs for smaller objects and a freelist for larger objects. Slab allocation can be accelerated by core-local caches, and several debug features are available.
• Logging infrastructure: fast and lock-free with support for several early outputs (uart chips, debugcon) and a built-in graphical terminal (based on gterm from the Limine bootloader).
  • Panic sequence with stack walker and symbol lookup.
• Global software clock, driven by a number of supported hardware timers: LAPIC, TSC, HPET, PIT, SBI timer.
• SMP-aware scheduler: round robin with per-core queues, work stealing and DPCs.
• VFS with a robust tempfs driver. File contents are sparsely cached in a global file cache.
• Loadable drivers and device management, partially automated by a device tree parser and PCI enumeration.
  • Notable drivers include: NVMe, virtio devices.
• Optional UB sanitizer, helpful for detecting bugs or increasing code size!

Build System:

• Uses stock core tools and GNU make, runs anywhere (tm).
• Xorriso is needed for generating bootable isos.

Glorious Screenshots

11/10/2023: Kernel panic while loading a malformed driver from the initdisk.

20/11/2022: x86 and riscv kernels running side by side in qemu.

Related Projects

• DreamOS64: another 64-bit OS by one of the northport contributors, Ivan G.
• OSdev notes: a repository of notes about various osdev topics. Feel free to contribute!

This is a complete rewrite of the original. If you're looking for that, it's available on the archive-2022-version branch.