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This chapter describes the Driver Loader Library (DLL) , a CFM shared-library extension to the Macintosh Device Manager. The DLL provides services to locate, install, and remove drivers.
Family experts and the Mac OS startup firmware are the primary clients of the DLL. It offers services that control every aspect of driver-to-device matching and driver loading and installation. Driver loading is normally an automatic process that frees drivers from having to match themselves with devices. In some situations, however, drivers may need to perform the match themselves.
The installation and removal services are provided for drivers that are called through the Device Manager. Typically, these drivers are of service type 'ndrv'. Clients that expect to call drivers through the Device Manager should utilize these services to locate the driver, load it, install it in the unit table, and remove it.
Clients of device drivers that belong to a well-defined family type (such as networking devices within Open Transport) need not use the installation and removal services, since these drivers are not callable via the Device Manager and hence do not reside in the unit table. These clients may choose to use the standard CFM services to load their drivers and may use the loader utilities to do driver matching before using the CFM.
The Driver Loader Library services provide several major functions for drivers:
Figure 9-1 shows the roles and relationships of the Device Manager, the ROM (all Macintosh system software other than the Device Manager), and the Driver Loader Library.
Figure 9-1 Position of Driver Loader Library
Figure 9-2 shows the relationship of the Driver Loader Library's main functions.
Figure 9-2 Driver Loader Library functions
