Kernelmoduulit

kernelmoduulit are modular components that extend the functionality of an operating system's kernel by providing device drivers, file systems, networking protocols, or other kernel services. Unlike built-in kernel code, kernelmoduulit are compiled separately and can be loaded into or removed from the running kernel without rebooting. This design allows optional hardware support, feature toggling, and easier maintenance.

In Unix-like systems such as Linux, kernelmoduulit commonly exist as binary objects (for Linux, .ko files). They declare initialization and cleanup entry points, and the kernel resolves dependencies among modules. The typical lifecycle includes loading with modprobe or insmod, usage while references exist, and unloading with rmmod or modprobe -r. Modules may register devices, create sysfs entries, or hook kernel subsystems.

Development and packaging usually require kernel headers and a compatible toolchain. Kernelmoduulit are written in C and must conform to the kernel's interfaces and ABI. Building a module uses a Makefile that invokes the kernel build system. Distribution packaging ensures the module matches the running kernel version and may integrate signing for security.

Security and stability considerations are central. Malicious or faulty modules can compromise the system, so many environments require module signing and enforce Secure Boot or lockdown modes. Administrators control loading with permissions and policy, and must ensure proper cleanup to avoid resource leaks or crashes.

Common use cases include device drivers for storage, network cards, GPUs, and sometimes kernel-level implementations of filesystems or virtualization features. While Linux supports loadable kernel modules widely, other operating systems offer similar mechanisms with their own terminology and tools. Portability across kernel versions is a continuing concern for module maintainers.

Overall, kernelmoduulit provide a flexible mechanism to extend kernel capabilities dynamically, balancing functionality, risk, and maintenance overhead.