Kernel
From Gentoo Linux Wiki
- Kernel
- The kernel is the core of an operating system, responsible for low level communication with a machine's hardware.
The kernel is a piece of software responsible for providing secure access to the machine's hardware and to various computer processes (a process is a computer program in a state of execution). Since there are many programs, and hardware access is limited, the kernel also decides when and how long a program should be able to make use of a piece of hardware, which is called scheduling. There are many different ideas about how scheduling should be done, and different schedulers are in different kernels.
Accessing the hardware directly can be very complex, since there are many different hardware designs for the same type of component. Kernels usually implement some hardware abstraction (a set of instructions universal to all devices of a certain type) to hide the underlying complexity from the operating system and provide a clean and uniform interface to the hardware, which helps application programmers to develop programs that work with all devices of that type. The Hardware Abstraction Layer (HAL) then relies upon a software driver that provides the instructions specific to that device's manufacturing specifications.
