Drivers for Character Devices
A character device does not have physically addressable storage media, such as tape drives
or serial ports, where I/O is normally performed in a byte stream. This
chapter describes the structure of a character device driver, focusing in particular on
entry points for character drivers. In addition, this chapter describes the use of
physio(9F) and aphysio(9F) in the context of synchronous and asynchronous I/O transfers.
This chapter provides information on the following subjects: