Open-source alternatives to Kernel

This project is an educational framework and toolkit designed for developing and testing operating system kernels. It provides a structured environment for implementing fundamental system primitives, including virtual memory management, preemptive process scheduling, and filesystem organization, using Rust and C. The framework is specifically oriented toward RISC-V and x86 architectures, serving as a laboratory for learning how to build core system software from the ground up. The project distinguishes itself by supporting both bare-metal deployment and hardware emulation, allowing developers

This project is a C-based heap management library designed for systems programming environments that require manual control over memory lifecycles. It provides the fundamental utilities necessary to initialize a designated region of memory and perform dynamic allocation and deallocation of memory blocks. The library utilizes a linked-list-based tracking system to manage memory segments, employing a first-fit strategy to locate available space within the heap. To maintain memory organization and minimize fragmentation, it implements boundary-tag coalescing, which automatically merges adjacent

This project consists of technical instructional guides and a structured computer science curriculum designed to teach the construction of a full computing stack from transistors up to a web browser. It provides a 12-week educational course that covers the fundamental domains of computer architecture and digital logic design. The curriculum is distinguished by its first-principles approach, guiding the learner through the engineering of CPUs, FPGAs, and PCBs using digital logic and hardware description languages. It includes specific syllabi for building a hardware design, a TCP/IP network st

This repository contains the complete source code for the OpenBSD operating system and its base utilities. It is a Unix-like operating system focused on a secure, portable, and multi-user environment, featuring a C-based system kernel that manages hardware resources and provides essential services. The project provides a source-based system construction model to compile the core kernel and base utilities from raw files. It includes a cross-compilation toolchain for generating the tools and headers necessary to build binaries for target architectures different from the host machine. The codeb

This operating system microkernel is written in Rust, focusing on safety, modularity, and POSIX compatibility for modern hardware. It implements a microkernel architecture that separates hardware drivers and system services into isolated userspace processes for fault tolerance, while providing standard Unix-like system calls and process primitives on a memory-safe codebase. The system handles low-level hardware abstraction through a virtual memory management layer that maps virtual addresses to physical pages uniformly across disparate architectures, alongside hardware memory management opera

XNU is an operating system kernel designed to manage system hardware and process execution across different processor architectures. It utilizes a hybrid microkernel design that combines microkernel message passing with monolithic kernel performance by embedding critical subsystems into a single address space. The project implements a port-based asynchronous messaging system for communication between kernel tasks and userspace processes. It manages hardware interactions through a layered driver architecture and enforces system-wide security policies via a mandatory access control interface.

The Linux kernel source tree is core system software tailored specifically for Rockchip processor architectures and embedded hardware boards. It manages hardware resources, processor execution contexts, memory allocation, and process scheduling for custom computing platforms. The project provides low-level hardware abstraction, initialization routines, and a collection of kernel modules designed to control integrated silicon components, storage, and networking hardware. The codebase incorporates hierarchical data structures to describe physical board layouts, memory maps, and peripheral conne

This project is a Linux kernel designed for Windows Linux integration, providing the underlying operating system kernel required to execute binary files and applications within the Windows Subsystem for Linux. It utilizes hypervisor-based virtualization to run a full kernel within a lightweight utility virtual machine managed by a Windows host. The repository enables the customization and compilation of the kernel from source. This allows for the modification of system behavior, the addition of specific drivers, and the tailoring of hardware compatibility for virtualized environments. The sy

rCore is a Rust-based operating system kernel and microkernel designed for Linux compatibility. It functions as a self-hosted development kit that implements a system call interface to support the execution of standard Linux userspace applications. The system is designed for modularity, featuring a mechanism for loading and integrating kernel modules into the active environment without requiring a system reboot. The kernel provides core operating system capabilities, including virtual memory mapping for process isolation, a disk-based file system for data persistence, and a layered network p

This repository provides the Android device kernel and the corresponding Linux kernel source tree. It serves as the foundational codebase for managing the hardware architecture and power management of mobile devices. The project includes a comprehensive mobile hardware driver set designed to manage device-specific components, such as CPUs, GPUs, and cellular modems. The source code supports activities including Android kernel customization, custom ROM development, Linux kernel auditing, and mobile driver development.

TinyGo is a specialized compiler and development toolkit designed to bring the Go programming language to resource-constrained microcontrollers and WebAssembly environments. It provides a bare-metal runtime environment that enables high-level code execution without the need for a traditional operating system, utilizing an LLVM-based backend to generate efficient machine instructions. The project distinguishes itself through aggressive optimization techniques tailored for small hardware, including a static memory allocation strategy and whole-program dead code elimination that significantly re

rpi4-osdev is a project for bare metal operating system development targeting the Raspberry Pi 4. It focuses on creating a custom operating system that runs directly on the hardware without an underlying kernel or abstraction layer. The project provides a codebase and instructional guide for developing a low-level system from scratch. This process involves transitioning from early boot code to kernel execution on the ARM64 architecture. The technical scope covers embedded system bootstrapping and low-level hardware interfacing. This includes managing memory-mapped I/O, physical address mappi

MicroPython is a lean implementation of Python 3 optimized to run on microcontrollers and other resource-constrained systems. It serves as a cross-platform embedded runtime and hardware abstraction layer, providing a firmware framework that maps high-level software commands to specific microcontroller registers across diverse processor architectures. The project functions as an embedded language interpreter that enables rapid prototyping on hardware through an interactive read-eval-print loop. It supports a wide range of target environments, including ARM, ESP32, STM32, RISC-V, and WebAssembl

Mezzano is a self-hosted operating system written entirely in Common Lisp. It employs a language-integrated kernel architecture where both the kernel and user-space applications execute within a single, unified high-level language runtime. The system is designed for both bare-metal environments, booting from physical external media, and as a guest operating system within virtual machine software. It implements symmetric multiprocessing to distribute computational workloads across multiple CPU cores. The environment includes capabilities for automated memory recovery via generational garbage

LiteX is an FPGA SoC development suite and SoC builder framework used to programmatically design system-on-chips. It provides a hardware description toolchain that uses a scriptable framework to define hardware layouts and automate the generation of hardware description language code. The project distinguishes itself by orchestrating multiple vendor and open-source toolchains to synthesize digital logic and generate deployable bitstreams. It supports multi-language logic integration, allowing disparate hardware description languages to be combined into a single project. The framework covers

smoltcp is a standalone TCP/IP network stack written in Rust, designed specifically for bare-metal and embedded systems. It provides a memory-safe implementation of the internet protocol suite that operates without requiring dynamic heap allocation. The project is distinguished by its heap-less memory management, using fixed-size buffers and manually allocated memory to ensure deterministic performance. It employs zero-copy packet processing and an interface-based hardware abstraction to decouple the network stack from physical hardware. The stack covers a broad range of networking capabilit

This project is a tutorial for developing a custom bare metal operating system specifically for the Raspberry Pi 4. It provides the guidance and resources necessary to write software that interacts directly with hardware without the use of a pre-existing kernel. The project centers on an ARM64 cross-compilation toolchain and a build pipeline that transforms source code into raw binary images. It utilizes linker scripts to define physical memory addresses and section placements, ensuring the resulting binary loads at the correct hardware entry point. The codebase covers direct hardware interf

Redox is a POSIX-compliant, microkernel-based operating system written entirely in Rust. By utilizing a memory-safe language for the kernel and all system components, the project eliminates common vulnerabilities such as buffer overflows and use-after-free errors. Its architecture relies on a minimal kernel that manages only essential hardware and process isolation, delegating all other system services to unprivileged user-space processes. The system distinguishes itself through a modular design where hardware drivers and system services run as independent user-space daemons, allowing them to

HyperDbg is a hardware-assisted kernel-mode debugging platform that leverages virtualization to monitor and control system execution. By utilizing hypervisor-level primitives, it enables deep system analysis and instrumentation without relying on standard operating system debugging interfaces. The framework provides a comprehensive environment for inspecting both kernel and user-mode processes, allowing for granular control over execution flow and system state. The project distinguishes itself through a transparent debugging layer designed to remain invisible to the target environment. It emp

This project is a freestanding kernel written in Rust that boots on x86 hardware without a standard library. It serves as a low-level system implementation focusing on the creation of a bare metal operating system. The system implements a bootable disk image toolchain that transforms source code into binaries compatible with a bootloader. It features a custom memory allocator for dynamic memory management and an x86 kernel implementation that includes paging, interrupt handling, and VGA text mode. The project covers several core capability areas, including low-level memory management through

Bitwise is a computer architecture education kit and a comprehensive set of guides for building a custom CPU, operating system, and compiler from scratch. It serves as a CPU design tutorial and a practical framework for implementing a unique instruction set architecture. The project provides a custom instruction set architecture toolchain, including resources for creating a matching assembler and compiler. It further includes a hardware development guide for synthesizing computer components and peripheral controllers for deployment on programmable logic devices and FPGAs. The kit covers full

This project is an educational operating system kernel designed to demonstrate the fundamental architectural principles of memory paging and process management. It is implemented as a minimal kernel that serves as a practical reference for building a functioning system from the ground up. The implementation features a preemptive multitasking kernel that switches execution contexts between threads to share a single CPU. It includes an x86 virtual memory manager that uses paging to map virtual addresses to physical memory and isolate processes. The system covers low-level hardware interfacing

This project is a comprehensive educational framework and curriculum designed to transition beginners into proficient security engineers. It provides a self-taught hacking curriculum centered on mastering system internals, programming, and attack techniques through structured pedagogical paths and recursive learning. The framework distinguishes itself by integrating a productivity system specifically for engineers, which combines block-based time scheduling and incremental task management to prevent burnout and overcome procrastination. It further connects technical growth to professional adv

This is a collection of academic programming projects that accompany an operating systems textbook, designed to teach core OS concepts through hands-on implementation. The projects span the major subsystems of an operating system, including process scheduling, memory management, file systems, and concurrency, with students building components from scratch in a simulated environment. The projects are structured to cover the full range of OS internals, from low-level kernel development to user-space system programming. Students implement lottery-based CPU schedulers, dynamic heap memory allocat

Computerraria is a digital logic circuit simulator and computer architecture educational tool. It provides a sandbox environment for building and testing functional computer systems by connecting modular logic gates and electronic wires. The project serves as a RISC-V architecture simulator that executes RV32I machine code using virtualized hardware components. It includes a virtualized CPU toolchain that uses containerized systems to compile source code into binary formats compatible with these custom processor architectures. The system covers digital logic circuit design and RISC-V ISA sim