Moon OS

Moon OS is a modular micro-kernel targeting the x86_64 and armv6 architecture, aiming to be POSIX-like in the future.

Screenshots:

Bootsplash:
Verbose boot:
Kernel panic:

Features

• Support for multiple architectures:
  • x86_64 PCs with acpi support
    • 4 level paging
    • Stacktrace/symbol backtrace
    • zoned bitmap and slab allocator.
    • System calls via syscall (No support for int based system calls)
  • Nintendo 3ds (armv6)
    • I2C driver
    • Bootrom IVT
    • Render strings to the display

Shared features (both architectures support this):

• ubsan
• Parsable boot arguments (quiet/verbose)
• Elf loader
• Primitive scheduler (Will be improved overtime, for now the my focus is on getting everything up and running (IPC, servers, libc, etc))

Future features:

• Threads
• kasan
• ACPI
• SMBIOS
• Multitasking
• Many hardware drivers including but not limited to:
  • Network cards
  • Storage drivers
  • GPU's
  • And much more
• A libc for the userland

Near future todo list

• Make better use of the APIC (currently it's used for the timer only)
• virtual memory subsystem
• New physical memory manager? (Unsure.)

This is currently being working on:

• Scheduler
• IPC
• Porting mlibc
• Initrd
  • In kernel decompression library to decompress the initrd
  • Native (build machine) program to build and add files (to maintain decent modularity) to the initrd.
  • Load and render an image from the initrd (tga, bmp)
• New additions to make the armv6 port a lot more usable (SD Card driver, gpu, vblank)

Directory walkthrough:

• libs/ -- Utilities not strictly related to a kernel (Scheduler, memory manager, etc), but required for it to function.
• kernel/ -- Kernel source code
• boot/ -- Everything Moon needs in order to boot
• daemon/ -- Special micro-kernel servers
• userspace/ -- Bootloader files, configs, modules, etc. Many files are automatically added at build-time.

Installation

Building: (assuming you are using a debian based distro)

• Install needed tools:

  • sudo apt update
  • sudo apt install gcc nasm qemu-system-x86 libfuse-dev

• Build kernel

  • make all -- Build the kernel
  • make run -- Run the kernel in qemu and build it if necessary (x86_64 only)
  • make kvm -- Run the kernel in qemu with kvm and build it if necessary (x86_64 only)
  • Command line options for kvm and run:
    • modern=yes -- Emulate modern features (x86_64 only)

• Configure architecture:

  • Simply edit two variables in Make.conf:
    • ARCH and BOARD. Permitted values are documented in a comment.

My journey: (Inspiration for newcomers)

I have always wanted to make an OS, so one day I decided to build one. Turns out it is a lot of work and back then it totally overwhelmed me to the point where I took long breaks (for months) because information was so scarce, and what little information there is is outdated.

I have written about 4 "kernels" during my OS development learning experience, and each time I started over because I was far too overwhelmed- none have gotten past a GDT :/ (heck, some where just bootloaders that called a kernel entry and looped)

If you are a beginner looking to understand what this code is doing and how you can write your own kernel with up-to-date information, please do join the OSDEV discord server (linked in the osdev wiki at the bottom) and don't give up when it gets hard at first.

I have started developing kernels about 8 months ago at the time of writing (with multiple month-long of breaks in between), and I still have many things to learn, however my try harder mindset proved useful in helping me get through the struggles and write a kernel for which I did not have to steal or copy code from tutorials or other projects out of a lack of knowledge.

I hope this inspired you to use this mindset when things seem too difficult to manage.

Best of luck ~ V01D (Tim).

Special thanks

• Thanks go out to websites like lowlevel.eu or the osdev wiki but also some cool and really helpful os developers on github and discord.

Finishing touch (resources I use)

• https://www.cs.cmu.edu/~ralf/files.html
• https://ethv.net/workshops/osdev/notes/notes-3.html
• https://osdev.wiki (barebones but up-to-date osdev wiki)
• https://wiki.osdev.org