Definition
Modular Kernel
A modular kernel is an OS architecture using a small core kernel with dynamic loadable modules. Modules (file systems, device drivers) can be loaded at runtime and removed when no longer needed, balancing the performance of a monolithic kernel with the flexibility of a microkernel.
Properties
Dynamic Extensibility
New hardware or file systems supported without recompiling the entire kernel.
Hardware Abstraction Layer
Modular kernels often include a HAL providing a consistent interface for modules.
Stability
More robust than pure monolithic design, but a bug in a loaded module still executes in kernel mode and can crash the system.
Efficiency
Modules communicate with the core through defined interfaces, avoiding message passing overhead of microkernels.