Differences Between a System Call and a User Function
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.