OSkernel

OSkernel is a conceptual operating system kernel used as a representative example in discussions of system design. It provides the essential services that run at the highest privilege level and interacts with hardware through a hardware abstraction layer.

Architecture: OSkernel follows a modular, loadable-kernel design that can be implemented as monolithic, microkernel, or hybrid, depending on configuration. It exposes a clean API for subsystems to be added or replaced, and supports portability across architectures with architecture-specific code isolated from core logic.

Core components: Process management, memory management, I/O and device drivers, interrupt handling, interprocess communication, and a virtual file system interface. The kernel enforces protection and isolation between processes through memory management and a defined privilege model. It provides system calls for user-space programs.

Scheduling and memory: OSkernel implements preemptive multitasking, priority-based or fair scheduling, and context switching. Memory management uses virtual address spaces, paging or segmentation, and a page table/TLB mechanism; it may include kernel and user-space memory isolation and optional garbage collection for runtime components.

I/O and file systems: OSkernel provides a unified interface for block and character devices, a virtual file system (VFS) layer, and support for multiple file systems. It supports asynchronous I/O and device buffering, and transfers data via DMA or programmed I/O.

Development and usage: OSkernel is described as open-source in many educational texts and is used to illustrate concepts such as synchronization, deadlock avoidance, and security. Real-world kernels such as Linux, Windows NT, and microkernel projects differ in specifics but share the same fundamental responsibilities.