Systemkall

Systemkall is a theoretical abstraction of the interface between user-space applications and the operating system kernel, proposed as a standardized, architecture-agnostic mechanism for invoking kernel services. It envisions a uniform way for programs to request resources and actions from the kernel, abstracting away architecture-specific calling conventions.

In this concept, applications issue requests through a defined set of descriptors that describe the operation, operands, and expected results, which are then translated by a mediation layer into architecture-specific system calls. The goal is to create a portable and predictable path from user space to privileged kernel code, reducing the need for bespoke wrappers for each platform.

The design aims to improve portability of runtimes, sandboxing, and security by constraining the surface area of the kernel interface and allowing centralized validation, auditing, and optimization of call paths. Core ideas often include a defined encoding for call descriptors, a small, stable virtual ABI, a mediator or gateway inside the kernel, and support for both synchronous and asynchronous calls.

Systemkall has appeared mainly in academic literature and experimental OS projects as a way to discuss cross-platform kernel interfaces and the tradeoffs among monolithic, microkernel, and exokernel designs. As a practical standard, it has not been adopted by major operating systems, but it informs discussions on system-call shrinking, kernel-user boundary hardening, and cross-OS runtimes.

Critics argue that the approach can introduce performance overhead, complexity, and entropy in the kernel, while proponents see potential gains in maintainability and security. See also: system call, API, kernel, microkernel, ABI, operating system.