Types of Windows drivers.

There are two basic types of Microsoft Windows drivers:

• User-mode drivers execute in user mode, and they typically provide an interface between a Win32 application and kernel-mode drivers or other operating system components.
• Kernel-mode drivers execute in kernel mode as part of the executive, which consists of kernel-mode operating system components that manage I/O, Plug and Play memory, processes and threads, security, and so on. Kernel-mode drivers are typically layered. Generally, higher-level drivers typically receive data from applications, filter the data, and pass it to a lower-level driver that supports device functionality.

Like the operating system itself, kernel-mode drivers are implemented as discrete, modular components that have a well-defined set of required functionalities. All kernel-mode drivers supply a set of system-defined standard driver routines.

The following figure divides kernel-mode drivers into several types.

As shown in the figure, there are three basic types of kernel-mode drivers in a driver stack: highest-level, intermediate, and lowest-level. Each type differs only slightly in structure but greatly in functionality:

1. Highest-level drivers, always depend on support from underlying lower-level drivers, such as intermediate-level function drivers and lowest-level hardware bus drivers.

2. Intermediate drivers, such as a virtual disk, mirror, or device-type-specific class driver. Intermediate drivers depend on support from underlying lower-level drivers.

3. Lowest-level drivers control an I/O bus to which peripheral devices are connected. Lowest-level drivers do not depend on lower-level drivers.

Date: 2015-01-29; view: 1621