User Mode Driver Framework

User Mode Driver Framework Development Concepts

• allows an intermediate driver to load in user mode
• cannot directly access hardware
• some drivers will be more stable in user mode
• reflector in kernel makes a user mode driver work as if it was a kernel mode driver

User Mode Driver Framework Architecture

The user mode driver framework is divided into two physical components.

• the user mode driver reflector, which reside inside the device manager.

• manages the user mode driver host processor.
• forwards the requests that are issued by the device manager.
• provides services for a user mode driver.

• the user mode driver host, which is a user mode application that is launched and managed bye the user mode driver reflector.
• it is used at the kernel's request to launch and to manage a user mode driver.
• it is responsible for mounting the API of a volume in order to receive forwarded requests from the user mode driver reflector.

Registry

• stores configuration information for applications, drivers, and the OS.
• OS uses registry to locate and load device drivers.
• Same basic setup as the desktop windows OS registry.
• space is limited, so keep any new entries short.

Device Manager

• manages devices and their interfaces.
• decides which drivers to load.
• uses registry to find drivers.
• runs continuously.