I/O request packets (IRPs) are kernel mode structures that are used by

Windows Driver Model In computing, the Windows Driver Model (WDM) also known at one point as the Win32 Driver Model is a framework for device drivers that was introduced with Windows 98 and Windows 2000 to replace VxD, which was used on older versions of Windows such ...

(WDM) and

Windows NT Windows NT is a proprietary graphical operating system produced by Microsoft, the first version of which was released on July 27, 1993. It is a processor-independent, multiprocessing and multi-user operating system. The first version of Win ...

device drivers to communicate with each other and with the

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also i ...

. They are data structures that describe I/O requests, and can be equally well thought of as "I/O request descriptors" or similar. Rather than passing a large number of small arguments (such as buffer address, buffer size, I/O function type, etc.) to a driver, all of these parameters are passed via a single pointer to this persistent data structure. The IRP with all of its parameters can be put on a queue if the I/O request cannot be performed immediately. I/O completion is reported back to the I/O manager by passing its address to a routine for that purpose, IoCompleteRequest. The IRP may be repurposed as a special kernel APC object if such is required to report completion of the I/O to the requesting thread. IRPs are typically created by the I/O Manager in response to I/O requests from user mode. However, IRPs are sometimes created by the plug-and-play manager, power manager, and other system components, and can also be created by drivers and then passed to other drivers. The I/O request packet mechanism is also used by

Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president un ...

's VMS operating system, and was used by Digital's

RSX-11 RSX-11 is a discontinued family of multi-user real-time operating systems for PDP-11 computers created by Digital Equipment Corporation. In widespread use through the late 1970s and early 1980s, RSX-11 was influential in the development of later ...

family of operating systems before that. An I/O request packet in RSX-11 is called a directive parameter block, as it is also used for system calls other than I/O calls.

References

External links

Whitepaper on Windows I/O model
*
IRP (Windows Drivers)
* Windows NT architecture Device drivers Data structures by computing platform Windows NT kernel OpenVMS {{Windows-stub de:IRP

See also

References

External links