Framework Architecture Overview

In the ChorusOS operating system, a driver entity is a software abstraction of the physical bus or device. Creating a device driver using the driver framework allows the device or bus to be represented and managed by the ChorusOS operating system. The hierarchical structure of the driver software within the ChorusOS operating system mirrors the structure of the physical device or bus.

Each device or bus is represented by its own driver. A driver's component code is linked separately from the microkernel as a supervisor actor, with the device-specific code strongly localized in the corresponding device driver.

Driver components are organized, through a service-provider/user relationship, into hierarchical layers which mirror the hardware bus or device connections.

The ChorusOS operating system diver framework can be considered in two ways:

• A hierarchical set of APIs that defines the services provided for and used by each bus or device driver at each layer of the architecture. This approach ensures portability and functionality across various platforms and continued validity of drivers across subsequent system releases.

• A set of mechanisms implemented by the ChorusOS microkernel, ensuring compliance and synchronicity with the ChorusOS operating system architecture and methods.

The driver framwork architecture is shown in the following figure.

Figure 3-1 Driver Framerwork Architecture

For details regarding the driver framework, see the ChorusOS 5.0 Board Support Package Developer's Guide.