PepperOS is a 64-bit freely-licensed monolithic kernel for x86 processors, with round-robin preemptive scheduling and 4-level paging. See the manual for more.

Trying the kernel in QEMU

Debian-based distributions

First, install the dependencies: sudo apt install nasm python3 xorriso make qemu-system

Then, you can get an x86_64 toolchain for compilation. The easiest way to do that on most systems is to install it from Homebrew:

brew install x86_64-elf-gcc

If you're already on a 64-bit machine (which you probably are), and don't want to install a cross-compiler, you can just override CC and LD variables in the Makefile, like so:

CC := gcc
LD := ld

Then, to compile the kernel and make an ISO image file, run: make build-iso To run it with QEMU, do: make run

Trying the kernel on real hardware

Compile the kernel and generate an ISO image like described above, then burn the image to a USB stick, /dev/sdX being the device name (you can get it using lsblk):

sudo dd if=pepper.iso of=/dev/sdX

TODO

The basics that I'm targeting are:

Basic utility of what we call a "kernel"

Implement tasks, and task switching + context switching and spinlock acquire/release
Load an executable
Filesystem (TAR for read-only initfs, then maybe read-write using FAT12/16/32 or easier fs) w/ VFS layer
Getting to userspace (ring 3 switching, syscall interface)
Porting musl libc or equivalent

Scalability/maintenance/expansion features

Documentation
SOME error handling in functions
Unit tests
Good error codes (like Linux kernel: ENOMEM, ENOENT, ...)

Optional features

In the future, maybe?

SMP support (Limine provides functionality to make this easier)
Parsing the ACPI tables and using them for something
Replacing the PIT timer with APIC

Thanks

PepperOS wouldn't be possible without the following freely-licensed software:

the Limine portable bootloader
Charles Nicholson's nanoprintf
Mintuski's Flanterm terminal emulator

...and without these amazing resources:

the OSDev wiki & forums
Intel 64 and IA-32 Architectures Software Developer's Manual
Documentation for the GNU Compiler Collection
dreamos82's OSDev Notes