OS X and iOS Kernel Programming

Accessing a Serial Port from User Space

To a user space application, a serial port driver is accessed as a standard character device in the /dev directory. This should be familiar territory for anyone who has accessed a serial port on any other UNIX system. Where the I/O Kit approach differs, however, is in how a user space application enumerates the serial ports that are present in a system. For many traditional UNIX applications, the user must specify the full path of the serial port's character file. The approach taken by Mac OS X is to shield users from the /dev directory, and to present available serial ports through a descriptive name. This is where the I/O Kit comes in.

Since a serial port is implemented by an I/O Kit driver, its driver ...