Microsoft Windows CE 3.0  

Registry Keys for USB Device Drivers

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Registry keys control how USB device drivers are loaded. When a USB device is attached, the USBD module loads the appropriate USB device driver to control that device, based on the device's configuration and interface descriptor information. The USBD module locates the correct driver by using a set of registry keys, which track both the drivers and the devices. The registry keys are stored as subkeys of the HKEY_LOCAL_MACHINE\Drivers\USB\LoadClients\key.

This loading method provides a flexible framework that allows drivers to be loaded in different contexts, depending on the range of devices that they are able to control. For example, OEMs may decide to include a generic class driver with their Windows CE–based platform that can control a broad range of USB devices. However, an IHV may have a driver for a specific USB device within that class that is more efficient or works better than the generic class driver. In this case, the IHV's driver could control a subset of the devices that the generic class driver controls, while allowing other devices to continue to be controlled by the generic driver. The structure of the LoadClientskey defines a framework in which programmers can specify driver precedence in great detail. The following are examples of the contexts that can cause specific USB device drivers to be loaded: