Open-source alternatives to Kernel

XNU is a hybrid operating system kernel that combines a microkernel architecture with a monolithic layer for system services. It provides a foundation for operating system development, incorporating standardized system-call interfaces, a modular device driver framework, and mandatory access control security. The architecture features a Mach-based microkernel and a BSD-based monolithic layer. It utilizes a message-passing inter-process communication bus for secure data exchange between isolated kernel components and user-space processes, alongside an object-oriented driver framework that decou

seL4 is a formally verified microkernel whose C implementation is backed by machine-checked mathematical proofs of correctness, confidentiality, integrity, and availability. It enforces strict isolation between processes through hardware-enforced address space separation and a capability-based access control system, where each process holds explicit rights only to the resources it has been granted. The kernel exposes hardware resources through a minimal API of system calls that manage threads, address spaces, and inter-process communication, with synchronous IPC supporting sender-identifying b

Asterinas is a memory-safe operating system kernel designed to prevent data races and memory corruption. It functions as a Linux-ABI compatible kernel, enabling the execution of existing Linux binaries and container workloads while providing a declarative operating system distribution model. The project distinguishes itself by acting as a virtual machine container host and a confidential computing guest OS, allowing it to run within hardware-isolated Trusted Execution Environments such as Intel TDX. It implements a minimal trusted computing base by isolating unsafe low-level operations and se

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

Kernel is an educational hobby operating system and low-level systems programming project written in Rust. Designed for students and hobbyists, the project provides a minimalist environment to explore computer architecture, CPU design, and kernel development directly on hardware without relying on a standard library or underlying operating system. The implementation features a freestanding language runtime and a custom target specification that replaces standard library components for bare-metal execution. It includes a multiboot bootloader interface to parse early-boot hardware handoff stat

TencentOS-tiny is a real-time operating system for microcontrollers designed to manage task scheduling and resource allocation across various hardware modules. It functions as an embedded platform and modular kernel for deploying real-time software on different chip architectures. The system includes built-in protocol stacks to enable secure data transmission and connectivity between terminal IoT devices and cloud platforms. The project covers real-time task management, embedded software deployment, and microcontroller administration. It utilizes a modular microkernel architecture and a har

NuttX is a POSIX-compliant real-time operating system designed for microcontrollers ranging from 8-bit to 64-bit architectures. It provides a deterministic execution environment with a real-time task scheduler and a POSIX embedded kernel to ensure portable code execution across diverse hardware targets. The project distinguishes itself through a comprehensive hardware abstraction layer that provides standardized drivers for I2C, SPI, CAN, and USB across various semiconductor chipsets. It also features an embedded networking stack supporting TCP, UDP, IPv4, and IPv6, alongside industrial proto

Limine is a multiprotocol operating system bootloader that bridges low-level hardware initialization and system software across legacy BIOS and modern UEFI firmware environments. It executes directly on bare-metal hardware without an underlying operating system kernel or standard C library, parsing storage media and filesystems during the early boot sequence before OS drivers load. The software targets diverse processor architectures including x86, ARM, RISC-V, and LoongArch through discrete target binaries built from shared source code. It reads files directly from FAT and ISO9660 storage f

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

NuttX is a POSIX-compliant real-time operating system designed for resource-constrained embedded environments. It functions as a scalable microcontroller OS that provides a Unix-like environment for managing hardware and running applications across architectures ranging from 8-bit to 64-bit. The system ensures high software portability by implementing a kernel that follows POSIX and ANSI standards. This allows developers to create portable embedded applications using standardized API calls across diverse hardware architectures. The project includes a modular kernel architecture and a hardwar

This project is a suite of system optimization tools for SteamOS designed to tune kernel memory parameters, manage swap space, and perform disk cleanup on handheld hardware. It provides a command-line interface for executing system tweaks and managing configurations without a graphical user interface. The toolset includes a kernel memory tuner for adjusting swappiness and page allocation, a swap space manager for creating and resizing virtual memory files, and a disk cleanup utility to remove orphaned shader caches and compatibility data. It also enables the relocation of game data and shader

WindowsCleaner is a set of administrative utilities for optimizing Windows storage through automated cleanup, file relocation, and system resource management. It functions as a disk cleanup tool and storage manager designed to reclaim space on Windows installations by removing temporary files and system junk. The tool provides specific capabilities to disable system hibernation to recover reserved disk space and migrate virtual memory paging files to different drives to free up storage on primary partitions. These operations are supported by system maintenance features that handle registry-b

This project is a collection of technical documentation and guides designed as a computer architecture explainer. It provides educational resources on how processors and operating systems execute programs, focusing on the fetch-execute cycle and the fundamental relationship between hardware and the kernel. The documentation covers a wide range of low-level system operations, including detailed guides on the executable and linkable binary format, virtual memory management, and kernel-level operations. It specifically explores the mechanics of CPU scheduling, preemptive multitasking, and the us

Mooncake is a disaggregated large language model serving platform and distributed key-value store designed for high-performance inference infrastructure. It functions as a GPU memory orchestrator and KV cache management system that pools and transfers key-value caches across clusters to accelerate inference. The system distinguishes itself by separating the prefill and decode phases of inference into distinct hardware clusters to optimize resource utilization. It utilizes a high-performance RDMA distributed cache with zero-copy transfers to move data between compute nodes, bypassing the CPU t

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.

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

xv6 is a Unix-like educational operating system designed for teaching kernel concepts. It is implemented as an instructional kernel for x86 and RISC-V architectures, featuring a virtual memory manager and support for symmetric multiprocessing. The system is designed to demonstrate core OS principles through a simplified re-implementation of Unix Version 6. It provides a controlled environment for studying system calls, trap handling, and process lifecycles. Its capability surface covers process management, including scheduling and context switching, and memory management via page tables for

nix is a Unix system API library and Rust system programming interface that provides type-safe bindings for invoking low-level system calls. It serves as a low-level operating system wrapper and POSIX compatibility layer, allowing for kernel interactions and administrative tasks through safe wrappers around platform-specific APIs. The project provides a kernel device interface for controlling hardware devices, managing kernel modules, and configuring terminal interfaces. It differentiates itself by offering type-safe wrappers for memory mapping and zero-copy input-output operations to reduce

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

ReactOS is an open-source operating system designed to be binary compatible with Windows applications and drivers. It consists of a low-level system kernel that manages hardware resources and a binary compatibility layer that enables the execution of software designed for the Windows binary interface. The project implements a cross-platform build system and toolchain for compiling and deploying bootable operating system images across different hardware architectures. This includes the use of cross-compilation toolchains and a hardware-abstraction layer to support various processor and motherb

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 tutorial and framework for building a low-level, bare-metal operating system from scratch using the Rust language. It focuses on ARMv8 kernel development specifically for the Raspberry Pi 3, providing the resources necessary to implement a monolithic kernel that runs directly on hardware without an underlying operating system. The project distinguishes itself by providing a complete embedded cross-compilation suite within a containerized environment to ensure consistent builds. It includes a dedicated kernel deployer that uses a serial interface and chainloader to load and b

This project is a bare-metal operating system developed for ARM64 architecture. It serves as a low-level implementation of kernel engineering, focusing on the fundamental construction of an OS from the hardware level up. The system is distinguished by its comprehensive approach to ARM64 processor control, featuring a red-black tree task scheduler and a hierarchical page table system for virtual memory management. It implements a sophisticated privilege model that handles transitions between kernel and user modes, ensuring process isolation through address space splitting and exception level m

CS-Xmind-Note is a collection of structured mind maps and conceptual diagrams serving as a comprehensive knowledge base for computer science fundamentals. It functions as an academic reference and study guide, organizing core subjects into a visual mapping of interdependent technical concepts. The project utilizes an XMind-compatible schema to model complex domains through hierarchical nodes and relational concept mapping. This approach allows for the visual representation of technical layers, linking hardware specifications to software abstractions. The knowledge base covers several primary

embedded-notes is a collection of technical study guides and development notes focused on embedded Linux, Linux kernel internals, and C programming. It serves as a reference for embedded systems development and a preparation resource for technical interviews in the field. The project provides detailed documentation on writing device drivers, managing virtual memory, and understanding kernel internals. It also includes guides on IoT network protocols, such as MQTT and TCP/IP, and outlines the architectural details of chip architectures and hardware peripherals. The material covers a broad sur

The Linux kernel is a monolithic operating system core that manages hardware resources, memory, and process scheduling across diverse computing architectures. It provides a standardized, POSIX-compliant environment for application execution while maintaining a modular driver framework that allows for the dynamic loading and removal of hardware interfaces. The project is distinguished by its high-performance concurrency toolkit, which utilizes lockless synchronization primitives and read-copy-update mechanisms to manage shared data access in multi-core environments. It incorporates a comprehen

Wasmer is a high-performance runtime engine designed to execute sandboxed WebAssembly modules across server-side, edge, and browser environments. It functions as a comprehensive platform for building, distributing, and running isolated applications, providing a secure and portable execution layer that maintains consistency across diverse hardware architectures and operating systems. The platform distinguishes itself through a robust toolchain that enables cross-language interoperability and the transformation of code into portable binary packages. It supports ahead-of-time binary generation t