41) Modes of the user and kernel.
User Mode User mode is composed of subsystems that transmit requests input \ output corresponding to the kernel mode driver manager by IO. The user level is composed of two subsystems - the environment (Environment) and integrated subsystem (Integral). The subsystem environment designed to run applications written for different types of operating systems. None of the sub-systems environment has no direct access to the hardware of the computer. Access to the resources of memory occurs through the virtual memory manager that runs in kernel mode. Also, the applications start with a lower priority than kernel mode processes. The integrated subsystem (Integral subsystem) monitors certain functions of the operating system on behalf of the environment subsystems. Consists of a security subsystem, the Workstation service and the Server service. The Security Service handles security tokens, allows or denies access to a user account, processes authorization requests and initiates the process of user logon. The Workstation service provides access to computer networks - is an API for the network redirector. The Server service allows the computer to provide network services. Kernel mode Windows NT kernel mode has full access to the computer's hardware and system resources. Working in a protected area of memory. Controls the flow, manages memory and the interaction with the hardware. Prevents access to critical memory areas of the application and the user-mode services. To perform these operations, user-mode process is to ask the kernel mode to execute it on their behalf. X86 architecture supports four privilege levels - from 0 to 3, but using only level 0 and 3. User mode uses a level 3, and kernel mode - 0. Kernel mode consists of executive services, which are the different modules that perform specific tasks, kernel driver, the kernel and HAL HAL The executive subsystem. Works with input \ output, the object manager, management of the processes and security. Unofficially divided into several sub-systems - the cache manager, configuration manager, the manager I \ O, a local procedure call, the memory manager, the security monitor Object Manager This is the executive subsystem that is referred to all the other modules of the executive subsystem, including system calls, when they need to access the resources Windows NT. The object manager is used to reduce duplication of objects, which may lead to errors in the system.
42) 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:
Highest-level drivers, always depend on support from underlying lower-level drivers, such as intermediate-level function drivers and lowest-level hardware bus drivers.
Intermediate drivers, such as a virtual disk, mirror, or device-type-specific class driver. Intermediate drivers depend on support from underlying lower-level drivers.
Lowest-level drivers control an I/O bus to which peripheral devices are connected. Lowest-level drivers do not depend on lower-level drivers.
43) One- and multilevel drivers.
Support for individual devices are often shared between several drivers, each of which provides the functionality necessary for the smooth operation of the device. Most drivers are managing physical devices are multi-level (layered drivers). Request processing IO split between several drivers. Everyone is doing its part. For example, a request to read a file is transferred the file system driver, buyout, following some operations (for example, splitting the query into multiple parts), passes it to "below" - the disk driver, and he, in turn, sends the request to the driver tires. Also among these drivers, you can add any number of filter drivers (for example, encrypting data). Querying the child driver (lower-level driver) sends the results "up" - a higher (higher-level driver). While the one-level drivers (monolithic drivers), which greatly simplify the whole process of writing and debugging.