Differences Between a System Call and a User Function

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A system call differs from a user function in several key ways.

  • A system call has more privilege than a normal subroutine. A system call runs with kernel-mode privilege in the kernel protection domain.
  • System call code and data are located in global kernel memory.
  • System call routines can create and use kernel processes to perform asynchronous processing.
  • System calls cannot use shared libraries or any symbols not found in the kernel protection domain.