User Space and Kernel Space

Kernel space and user space are memory region which differs in the privilege of their components.

Kernel Space:

  • It is a part of memory where the code of the kernel is located and executed under.
  • The components used in kernel space are referred to as kernel space components.
  • Processes running under this space have full access to the kernel and do not require any system calls to avail of service provided by the kernel.
  • They can access any machine instruction of the underlying architecture
  • They can access h/w controllers and register as per to rules.
  • Example: getpid, socket, read, write, open, process management subsystem, memory management subsystem are system space or kernel space components.

User Space:

  • It is a set of locations where normal user’s processes run that is space other than kernel space.
  • This area is often referred to as userland and components are referred to as user space components, the code that runs outside the operating system’s kernel.
  • Userland usually refers to the various programs and libraries that the operating system uses to interact with the kernel.
  • Processes running under this pace do not have the full privilege and do not have access to kernel space.
  • They can access a small part of the kernel by using system calls.
  • They cannot access all the machine instructions and can access h/w controllers and register with the help of system calls.
  • Examples: Any C program or top, ps, ls, malloc, fopen are common user space program which evokes system calls to get the job done.

Diag-1: User space and Kernel Space

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Categories: Operating system (OS)

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