Introduction

Modern operating systems provide a clear separation of the kernel processes from those running in user space, which prompts the question of how to access I/O devices from user processes, without breaking the above mentioned architectural separation, which guarantees stability, security and performance.

Several approaches are available, depending on the level of abstraction used and the context of the problem. One of the solution is using POSIX Device Files, which indeed provide the same system-call interface for both files and devices. This article will describe the POSIX standard, the POSIX device files, and give a short enumeration of advantages and disadvantages of them. Continue reading →