Linux Kernel Space and User Space
Linux Kernel Space and User Space
In a Linux operating system, the memory is divided into two main parts: Kernel space and User space. This separation helps ensure system stability, security, and efficiency. It allows regular applications to run without directly affecting the core parts of the operating system. Understanding this distinction is essential for anyone learning Linux or working with operating systems.
Linux Kernel
The Linux Kernel is the core component of the operating system. It manages hardware resources and provides essential services like process management, memory management, file systems, and device control.
The Kernel is like the brain of the system, while applications and programs run in a separate area known as User Space. It acts as a bridge between applications and the hardware of a computer. It controls all hardware operations like memory, CPU, input/output devices, and manages system resources. The kernel runs in a privileged mode with full access to hardware.
When the Linux kernel completes its initialization, it starts the systemd process as the first userspace program (PID 1).
Kernel Space
Kernel space is where the Linux kernel runs and has full access to the hardware. Code running in kernel space can execute privileged instructions and directly interact with physical devices.
Kernel Space is the memory area where the Linux Kernel executes and provides its services. Only the Kernel has access to this space, and user programs cannot directly access it. It handles low-level tasks such as managing memory, scheduling processes, and handling system calls. This space is protected to prevent user applications from accidentally or maliciously damaging the system.
User Space
User space is where all the user applications run, such as web browsers, text editors, games or custom programs. These applications run with limited permissions and cannot directly access hardware or kernel memory. Instead, they use system calls to request services from the kernel.
Kernel Space vs User Space
| Kernel Space | User Space | |
|---|---|---|
| Definition | Area where the Kernel runs and provides system services | Area where user applications and programs run |
| Access Level | Full access to system resources | Restricted access |
| Purpose | Runs the core parts of the OS | Runs user applications |
| Security | Highly privileged and protected | Isolated from the kernel. Less privileged, restricted from direct hardware access |
| Crash Impact | Can crash the entire system | Only the application crashes.Errors usually affect only the specific application |
| Example | Memory manager, process scheduler, device drivers | Text editors, web browsers, games, etc |
