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Making Hardware Accessible to Applications

Let's assume you have written a driver for a device, have thoroughly tested it, and are ready to deploy it. Is your job done? Not necessarily, because there is the perennial problem for driver writers of making their service accessible to user processes. A driver without clients in user space is useless (unless all of its clients reside in the kernel).

This chapter does a few things to help you on this score. It describes the architectural aspects of Mac OS X and the Darwin kernel that underlie the transport of data across the boundary separating the kernel and user space. It describes the alternative APIs on Mac OS X for cross-boundary transport between a driver stack and an application. And it describes how to roll your own solution by writing a custom user client, finally taking you on a detailed tour through an example implementation.

To better understand the information presented in this section, it is recommended that you become familiar with the material in I/O Kit Fundamentals and the relevant sections of Kernel Programming Guide.

Contents:

Transferring Data Into and Out of the Kernel
Writing a Custom User Client
A Guided Tour Through a User Client

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