In Linux, there are two primary user modes, known as User Mode and Kernel Mode.
* User Mode : User Mode is the default mode in which user-level applications, processes, and programs run. In this mode, applications have restricted access to the system’s hardware and resources. They interact with the kernel through system calls to request services or perform privileged operations. User Mode provides a level of isolation and protection, preventing user-level processes from interfering with critical system operations.
* Kernel Mode : Kernel Mode, also known as Supervisor Mode or Privileged Mode, is the mode in which the operating system’s kernel executes. In this mode, the kernel has access to the full range of hardware and system resources, and it can execute privileged instructions and perform critical tasks, such as managing memory, handling interrupts, and controlling hardware devices. Kernel Mode is more privileged than User Mode and is responsible for managing the system and providing services to user-level processes.
The transition between User Mode and Kernel Mode occurs through system calls. When a user-level process needs to perform a privileged operation or access hardware resources, it requests the kernel’s assistance through a system call. The kernel then switches to Kernel Mode to fulfill the request, and after completing the operation, it returns control to User Mode.
The separation of User Mode and Kernel Mode helps ensure system stability, security, and protection, as the kernel controls and manages critical operations while user-level processes operate in a more restricted environment.
