System Call

Definitions

1. The interface between a user-space program and the operating system kernel. When a program needs OS services (file I/O, network, process creation, memory allocation), it makes a system call which transfers execution to the kernel. The boundary between user mode and kernel mode. Linux has ~450 syscalls; strace traces them.

   In plain English: A request from your program to the operating system to do something privileged, like reading a file or opening a network connection.

   Example: "Every file read, network send, and memory allocation ultimately goes through a system call — strace shows you exactly what your program asks the OS to do."

Related Terms

• ABI
• Allocator
• Architecture
• C Interop
• Interoperability
• Interrupt
• Ownership
• Loadable Module
• Linux Kernel Module