user - mode driver framework
for ways to use these extensions, see user - mode driver framework debugging .
user mode driver framework architecture (windows embedded ce 6. 0) | microsoft docs
this topic describes the advantages of writing a user - mode driver framework (umdf) driver instead of a kernel - mode driver .
when a driver is flagged as a user mode driver in the registry, the device manager will access the user mode driver reflector. the user mode driver reflector launches the appropriate user mode driver host process and forwards i / o requests to it. the user mode driver host process in turn forwards i / o requests to the user mode driver .
the user mode driver framework is divided into two physical components. the first component is the user mode driver reflector, which resides inside the device manager. the second component is the user mode driver host, which is a user mode application that is launched and managed by the user mode driver reflector .
in an implementation, non - hardware kernel stub interfaces may be provided by a user - mode framework reflector 108. the user - mode framework reflector 108 may be a kernel - mode windows device mode (wdm) filter driver that is installed at the top of a kernel - mode device stack for each device that a user - mode framework driver 101 manages. the user - mode framework reflector 108 manages communication between the kernel - mode components and the user - mode driver host process .
microsoft user - mode driver framework feature pack 1. 0 - add or remove programs entry information
user - mode driver framework version 1. 11 update for windows 7, and windows server 2008 r2
user - mode driver framework: technical synopsis peter wieland development lead windows device experience group microsoft corporation .
extension commands that are useful for debugging user - mode driver framework drivers are implemented in wudfext. dll .
windows 10, version 1803 (redstone 4) includes kernel - mode driver framework (kmdf) version 1. 25 and user - mode driver framework (umdf) version 2. 25 .
kernel - mode driver framework (kmdf) version 1. 11 update for windows 7
the process of using a user mode driver begins with a user application or with a parent bus driver. user applications and parent bus drivers can load user mode drivers by calling activatedevice or activatedeviceex. user applications and parent bus drivers can unload user mode drivers by calling deactivatedevice. once loaded, any user application or driver can access the user mode driver by using the device handle .
in this topic, you' ll learn about the naming conventions for the file names of the kernel - mode driver framework (kmdf) library and the user - mode driver framework (umdf) library .
add or remove programs entry for microsoft user - mode driver framework feature pack 1. 0. microsoft' s user - mode driver framework feature pack is a component of windows media player 11 required to interact with zunes and other peripherals .
18. the device driver framework of claim 17, wherein the user - mode module is stopped and a driver call stack is unwound .
urltoken; note: the asterisks and different addresses allow your urltoken to update the kernel - mode driver framework to that do not have the 1. 11 version of kmdf, windows 7 sp1, windows7. the kernel - mode driver framework (kmdf) version 1. 11 update contains the following changes: kernel - mode driver framework version 1. 11 update for windows. error code 8004402f for important update for kernel - mode driver framework version 1. 11 for windows 7 update for kernel - mode driver framework version. update for kernel - mode driver framework version 1. 11 for windows 7 (kb2685811) keeps failing error 8007007e? upload failed. resolve imaging issues with your drivers and dell hardware by updating your kernel mode driver framework to 1. 11. client portal log in newsletter sign up kk remote. update for kernel - mode driver framework update for kernel - mode driver framework version 1. 11 for windows 7 failed error details: code 80041002 update. windows 8. 1 includes user - mode driver framework (umdf) version 2. 0 and kernel - mode driver framework iot core updates; windows 8. 1 includes user - mode driver. unable to install windows update: update: update kernel - mode driver framework. i am unable to update the kernel - mode driver framework ver 1. 11 for windows. windows update - kernel - mode driver framework version kernel - mode driver framework version 1. 11 failed update; i have been getting a
windows framework driver. kernel - mode driver framework version 1. 11 update for windows that have failed. and install version 1. 11 of the files. during driver .
this section contains information that applies only to user - mode driver framework (umdf) versions 1. 11 and earlier .
this topic lists available user - mode driver framework (umdf) sample drivers that you can download from the windows driver samples repository on github .
18. windows user mode driver framework virtual printer driver clr host. net data converter. net data converter. net data converter native native native
the following diagram shows how driver host processes, driver manager, and reflector communicate across the user mode / kernel mode boundary .
at 206, the umdf user - mode code prepares a dma transfer. the user - mode framework driver 101 may invoke the kernel stub 106 to perform device programming for this dma operation .
download user - mode driver framework version 1. 11 update for windows 7, and windows server 2008 r2 from official microsoft download center
kernel and user mode driver framework 1. 11 update - what it is and why you need it! - updated! ! !
figure 1: microdrivers split device driver functionality between a kernel - mode component and a user - mode component .
this topic describes how the driver manager builds a user - mode device stack, and how the host process, reflector, and driver manager process an i / o request that an application sends to a user - mode driver framework (umdf) driver .
for a complete description of the extension commands in wudfext. dll, see user - mode driver framework extensions (wudfext. dll) .
providing the user - mode driver and the kernel stub at a same interrupt level .
the user mode driver has restricted access rights to the hardware, which prevents it from being able to accommodate requests such as mapping physical memory or calling interrupt functions. to accomplish these types of requests, the user mode driver calls the user mode driver reflector, and enables the user mode driver reflector to handle the request. the user mode driver reflector then checks the user request against the registry settings to determine whether it should perform the requested action. unlike with interrupts and the mapping of physical addresses, the user mode driver can, via the device handle and without the aid of the user mode driver reflector, access the parent bus driver regardless of where the parent bus driver is located .
stopping user - mode driver execution if a device exception is encountered using the reset stub .
at 308, the user - mode framework reflector 108 sends a software interrupt to the user - mode framework driver 101 to take control of the processing. at 310, the user - mode framework driver 101 may synchronize access with registers and other resources. the isr or kernel stub 106 may queue a deferred procedure call to finish i / o operations at a lower priority (irql) than that at which the isr executes .
i am sure you' ve heard a lot about the kernel mode driver framework (kmdf), the new paradigm for writing kernel mode drivers for windows. but have you heard about the user mode driver framework (umdf)? this article introduces umdf and gives a brief overview of its architecture .
the driver host process loads vendor - supplied umdf drivers and framework dlls, provides an execution environment for user - mode drivers, and routes messages between drivers in a user - mode stack. for more information, see umdf driver host process .
the umdf driver is an in - process com component that controls the hardware from user mode .
the user mode driver reflector, which is aware of the original process and the destination process, uses cefsiocontrol to forward the device manager' s request to the user mode driver host. the user mode driver host then parses the request to either load, unload, or call the parent bus driver' s entry .
the reflector is a kernel mode wdm filter driver that is installed at the top of the kernel mode device stack for each device that is managed by a umdf driver. the reflector manages communication between the kernel mode components and the user mode driver host process .
synchronizing the kernel stub and the user - mode driver using a deferred procedure call (dpc) .
a combination of the kernel stubs, the software based fault isolation mechanism 107, or the user - mode framework reflector 108 may monitor for an interrupt storm and reset the device if one occurs. in some implementations, upon detection of an interrupt storm, the isr may be routed through the user - mode framework reflector 108, or there may be some communication between a kernel interrupt dispatcher and the user - mode framework reflector 108 such that the user - mode framework reflector 108 can detect or be notified when a device is causing an interrupt storm. the user - mode framework reflector 108 may then call stub _ reset (i. e. , the reset stub 105), and then either notify or terminate the host driver .
if the driver is a user mode driver, the call to activatedevice or to activatedeviceex will result in the device manager calling the user mode driver reflector function as well. a driver is recognized as a user mode driver when the flags value is set to the setting devflags _ load _ as _ userproc (0x10) in the registry key of the device .
user - mode driver framework (umdf) debugging extensions are implemented in the extension module wudfext. dll. you can use these extensions to debug drivers that use umdf .
in an implementation, a dma device for a user - mode framework driver is one that implements no device specific kernel code. the device may have the following attributes :
you can debug a umdf driver by using user - mode debuggers or kernel - mode debuggers. for more info, see debugging wdf drivers .
all wdf driver samples and visual studio driver templates are universal windows driver compliant .
windows driver frameworks (wdf) is a set of libraries that you can use to write device drivers that run on the windows operating system. wdf defines a single driver model that is supported by two frameworks: kernel - mode driver framework (kmdf) and user - mode driver framework (umdf). this topic provides answers to frequently asked questions about umdf .
in some implementations, drivers are written completely in a user - mode framework. no code in the kernel results in a very stable implementation, where generic driver functions from a split driver model are sufficient .
similar to a kernel - mode stack, the construction and tear down of a user - mode stack is driven by plug and play (pnp) events. after the kernel - mode stack has been built, the reflector notifies the driver manager to start construction of the user - mode stack. the driver manager launches the driver host process and provides sufficient information to the launched process to build the user - mode stack. in this way, the user - mode stack can be considered an extension of the kernel - mode stack .
the user - mode framework reflector 108 may invoke the kernel stubs to handle requests for “stub operations” in response to xksoperation calls in the xks _ uapi. the user - mode framework reflector 108 may call a kernel stub interface at dirql holding the proper locks in a manner that allows for safe execution of the kernel stubs using xfi. in an implementation, the downcall interface for the user - mode framework reflector 108 to call an kernel stub operation could be :
the run - time environment dispatches i / o requests, loads the driver, constructs and destroys the user mode device stack, manages a user mode thread pool, and handles messages from the reflector and the driver managers .
the run - time environment dispatches i / o requests, loads the driver, constructs and destroys the user mode device stack, manages a user mode thread pool, and handles message from the reflector and the driver manager .
how does a user i / o sent to a umdf driver get processed? as figure 1 shows, a user mode application sends its requests to kernel mode as for any device. once in kernel mode, the reflector sends the requests to the proper wudfhost process running in user mode for processing. the action of the requests is totally transparent to the application - - only the umdf driver knows it is running in user mode .
this topic provides a high - level overview of user - mode driver framework (umdf) components and describes how your driver interacts with system - supplied components. it applies to both umdf versions 1 and 2 .
windows driver frameworks (wdf) contains umdf, a framework for the creation of user - mode drivers. like kernel - mode driver framework (kmdf), umdf provides an abstraction layer from wdm, handling much of the plug and play (pnp) and power management functionality, and allowing the driver to opt in for specific functionality and event handling .
a reflector to manage communication between the user - mode module and the kernel stub .
when a driver is in user mode, the pbuscontext passed into activatedeviceex must be a dword instead of a pointer .
a umdf driver can receive i / o requests from a kernel - mode driver. for more info about kernel - mode clients, see supporting kernel - mode clients in umdf 2 drivers .
if you built your driver using a version of the kmdf library that is more recent than the version of the framework that is on the system, then the latter must be updated. for information about updating the framework library, see redistributable framework components .
. second, it must move the remaining (non - critical) functions to a user - mode component, and generate code for communication between the kernel - mode and user - mode components. this is achieved by the
a microdriver consists of a kernel - mode component that implements critical functionality and a user - mode process that implements non - critical functionality. device driver functionality is split between the kernel - mode and user - mode components at function boundaries. the two components communicate using an lrpc - like mechanism [
the driver host process provides the execution environment for user - mode drivers and routes messages between drivers in the user - mode stack. the reflector uses a message - based interprocess communication mechanism to communicate with the driver manager and host process .
into microdrivers. this provides a path to execute device drivers written for commodity operating systems in user - mode without sacrificing performance. prior efforts at user - mode device drivers have either required rewriting the driver completely [
the umdf driver is an in - process component object model (com) component that controls the hardware from user mode .
user - mode drivers operate in a much simpler environment than kernel - mode drivers. for example, kernel - mode drivers must take into account irql, page faults, and thread context. in user mode, however, these issues do not exist. user - mode drivers always run in a different thread from the requesting process and can always take page faults .
19. the device driver framework of claim 18, wherein the kernel stub calls a deferred procedure call (dpc) to synchronize with one of an interrupt service routine and the user - mode module .
for an overview of how to debug user - mode driver framework (umdf) drivers, including information on how to start this kind of debugging session, see the debugging umdf drivers section of the windows driver kit (wdk) documentation .
providing the kernel stub access to a shared memory space that is shared between the kernel stub and the user - mode driver .
sharing information between the user - mode driver and the kernel stub regarding the hardware device and the interrupt in a shared memory .
you can debug umdf drivers by using either a user - mode debugger or, starting with umdf version 2, a kernel - mode debugger .
when protecting systems against kernel mode drivers using the software fault isolation mechanism 107, the software isolation augments the kernel mode driver such that driver exceptions may be detected. when the software isolation code detects a driver exception, it stops the driver code and unwinds the driver call stacks to return a proper error code back to the user - mode framework reflector 108. the user - mode framework reflector 108 in turn calls a driver provided reset stub 105 that functions like a “kill switch” to stop the hardware from any further operations which may corrupt the system states. the reset stub 105 is provided by the driver at the driver initialization. the “kill switch” stops the hardware immediately, including any outstanding dma transfers .
in some implementations, a method includes loading a user - mode driver associated with a device; loading kernel stubs having a reset stub associated with the user - mode driver in a kernel of an operating system; receiving an interrupt; invoking the kernel stub to perform an interrupt service routine; monitoring for an exception; and obtaining information about the interrupt using the user - mode driver .
the user - mode framework reflector 108 may forward i / o, power, and plug and play messages from the operating system to the driver host process, so that user - mode drivers can respond to i / o requests and participate in plug and play device installation, enumeration, and management. the user - mode framework reflector 108 or the software based fault isolation mechanism 107 may also monitor the driver host process to ensure that it responds properly to messages and completes critical operations in a timely manner, thus helping to prevent driver and application hangs .
when debugging a umdf driver, you can merge framework logs with driver logs by issuing: ! wdfkd. wdflogdump < drivername. dll > - m
figure 1 shows the overall architecture of a umdf driver. a umdf driver runs in a driver host process that also hosts umdf and a run - time environment. each such driver operates as part of a stack of drivers that manage a device. the user mode drivers are loaded above the kernel mode drivers at the top of the stack. because user mode components do not have access to the system address space where the system and kernel mode drivers maintain i / o requests and other shared data, the umdf architecture includes components that communicate between kernel mode and user mode .
the user mode driver framework (umdf) is one of two major sub - frameworks in the windows driver foundation (wdf) framework. it in essence sits on top of the windows 7 operating system, and uses the windows win32 api’s primarily to communicate with the operating system, which ultimately communicates with the computer system hardware device .
user - mode and kernel - mode drivers have different structures, different entry points, and different system interfaces. whether a device requires a user - mode or kernel - mode driver depends on the type of device and the support already provided for it in the operating system. most device drivers run in kernel - mode. kernel - mode drivers can perform certain protected operations and can access system structures that user - mode drivers cannot access. moreover, kernel - mode drivers often offer lower - latency services. however, kernel - mode drivers can cause instability and system crashes if not implemented properly, as well as introduce security vulnerabilities .
] offer apis to program user - mode device drivers that communicate with a kernel module. chubb [
as figure 2 shows, the user mode driver runs under the host process, which combines with kernel mode drivers (including the reflector) to form the device stack for the device .
this solution demonstrates how a user - mode driver framework (umdf) version 2 driver can implement f - state - based power management. the singlecomp project demonstrates how a umdf version 2 driver can implement f - state - based power management for a device that has only a single component .
my copy of windows 7 is pirated and i want to use my xbox one controller with it but that requires a few updates, user - mode driver framework version 1. 11 and kernel - mode driver framework version 1. 11 to be exact. i' m wondering if instaling these will make windows realise my copy isn' t genuine, so is it safe to install these updates ?
the request is either completed by one of the drivers in the user - mode stack or forwarded by one of the drivers back to the reflector. when the reflector receives a request from the user - mode driver stack, it sends the request down the kernel - mode stack for completion .
]. in the kernel - mode component, direct calls to functions implemented in the user - mode component are replaced with upcalls through stubs. stubs marshal data structures accessed by the called function and unmarshal them when the call returns. a symmetric downcall mechanism enables the user - mode component to invoke kernel functions. to handle multiple requests from the kernel - mode component, the user - mode process is multithreaded .
20. the device driver framework of claim 19, wherein the user - mode module and the kernel stub are provided at a same interrupt level, and wherein the dpc processes i / o requests at a lower interrupt level .
as figure 4. 1 shows, windows supports a layered i / o architecture. user mode applications and services issue i / o requests through the win32 api and communicate with the user mode pnp manager to perform plug and play and power activities. the win32 api and user mode pnp manager, in turn, communicate with the kernel mode i / o system, which includes the kernel mode i / o manager, pnp manager, and power manager. the kernel mode i / o system communicates with the kernel mode drivers .
the reflector is a kernel mode wdm filter driver that is installed at the top of the kernel mode device stack for each device that a umdf driver manages. the reflector manages communication between the kernel mode components and the user mode driver host process. the reflector forwards i / o, power, and plug and play messages from the operating system to the driver host process, so that user mode drivers can respond to i / o requests and participate in plug and play device installations, enumeration, and management .
if you have a debugger connected, you can access both the driver and framework ifr logs by issuing! wdfkd. wdflogdump .
the windows kernel creates i / o request packets (irps) to represent the user mode i / o requests and forwards them to the top of the kernel mode driver stack for the target device .
a user - mode driver can impersonate its client process only for i / o requests, and not for plug and play or other system messages .
at 216, it is determined if an exception occurred. the exception may be an interrupt storm. the sfi 107 detects exceptions in kernel mode. the reflector 108 receives the indications of exception in kernel mode and takes actions to stop driver at 216. at 218, the driver call stack is unwound, and at 220 the hardware is stopped in kernel mode without signaling the user mode driver .
when you build your driver, the msbuild utility links the driver with a stub file that contains the version number of the library that the msbuild utility used. when the operating system loads your driver, the framework' s loader checks the version information in your driver' s stub to determine if the driver will run with the version of the framework library that is on the system .
the framework exposes the user mode ddi, which is a dynamic - link library (dll) of com - style objects that support the presentation, flow, and management of i / o, power, and plug and play requests to the driver .
drivers in operating systems run in either user - mode or kernel - mode. user - mode drivers run in the non - privileged processor mode in which other application code, including protected subsystem code, executes. user - mode drivers cannot gain access to system data or hardware except by calling an application programming interface (api) which, in turn, calls system services. kernel - mode drivers run as part of the operating system' s executive, the underlying operating system component that supports one or more protected subsystems .
run device drivers as user - mode processes. a bug exercised in a device driver only results in the failure of the user - mode process running that driver. this approach, however, has two key problems. first, this architecture is not compatible with commodity operating systems, which are designed as monolithic kernels. providing support for user - mode device drivers in commodity operating systems thus requires kernel modifications and rewriting device drivers [
yes. even if your driver requires access to some kernel - mode resources or features, you might be able to split your driver into two parts. this approach enables you to benefit from some of the advantages of developing and running drivers in user mode .
the kernel stubs may also provide sequencing of operations for hardware devices where certain sequences of operations are timing sensitive and cannot tolerate pauses incurred by context - switching out a user - mode driver. where a pure user - mode driver would have to be scheduled onto a cpu to acknowledge each of the interrupts, the kernel stub _ isr 106 reduces this latency because it is invoked by the kernel - mode interrupt handler and may run in an arbitrary context at a raised irql. the user - mode framework driver 101 may support multiple devices, and therefore may multiplex requests from multiple devices through a single instance of the kernel stub _ isr 106 .
17. the device driver framework of claim 16, wherein if the software based fault isolation mechanism detects an exception, the device is stopped .
a user - mode driver is started by the driver manager and runs in a driver host process. a single instance of the driver can service simultaneous requests from multiple applications. to communicate with the driver, applications issue i / o requests to the driver' s device through the win32 api. the primary entry point in a user - mode driver is the idriverentry interface (umdf 1. 11 and earlier) or the driverentry routine (starting in umdf 2. 0), rather than a main () function .
startup / shutdown and error - handling). the user - mode component is implemented as a standalone process that is called from the kernel - mode component. together, they provide the functionality of a traditional device driver .
although this chapter focuses on kernel - mode drivers, windows includes a growing number of drivers that actually run in user mode, as previously described, using the user - mode driver framework (umdf) that is part of the wdf. before finishing our discussion on drivers, we’ll take a quick look at the architecture of umdf and what it offers. once again, for a much more complete overview on the subject, please refer to urltoken .
the process of moving the driver package to the target computer and installing the driver is called deploying the driver. you can deploy a driver sample automatically or manually .
down in kernel mode, the umdf kernel mode reflector driver (or simply reflector) provides the necessary connections between user mode and a kernel device stack. there is one reflector device instance installed in each kernel umdf device stack. the reflector is responsible for forwarding i / o, power, and pnp messages from kernel mode to the host process .
this section describes user - mode driver framework (umdf) and details the differences between umdf versions 1 and 2. it also provides high - level architectural information about umdf. use this section to determine if a umdf driver is the right choice for your needs, and to decide which umdf version to use .
16. the device driver framework of claim 15, wherein the kernel stub invokes an interrupt service routine in response to an interrupt received from a device; and wherein the software based fault isolation mechanism monitors for exceptions thrown by a device associated with the user - mode module .
at 210, a hardware device raises an interrupt. executable code within kernel stub 106 for the isr is invoked that copies volatile device state into the sdd memory 104. at 212, the user - mode framework driver is signaled. this may be performed through the isr execution .
]. we show that program analysis techniques can automatically identify critical functions in a device driver, following which a semantics - preserving transformation can split the driver into a user - mode and a kernel - mode component. we discuss the design and implementation of such a refactoring tool in
the driver includes code to handle only those events for which its device requires device - specific support. all other events can be handled by framework defaults .
optimizing device drivers for terminal servers plug and play device redirection framework gaurav daga program manager windows terminal server microsoft .
microsoft believes that by moving these types of drivers to user mode, it will simplify driver writing and improve the overall stability of the windows operating system. i certainly agree with this statement since user mode is a much more forgiving environment. let' s face it, if you can develop a driver for a device without having to worry about the complexities of kernel mode programming or risking crashing a user' s machine when it misbehaves, your customers and microsoft will be much happier .
for more information about using msbuild to build a driver package, see building a driver .
as the name implies, a umdf driver runs in user mode, specifically in a process running the executable image wudfhost. exe. the general layout of umdf modules is shown in
umdf is based on the same conceptual driver programming model as the kernel mode driver framework (kmdf) that is also part of wdf. however, the two frameworks implement the model with different components, device - driver interfaces (ddis), and data structures. kmdf includes some objects that are available ...
to make porting code easier from kernel mode to user mode, and to keep a consistent architecture, umdf uses the same conceptual driver programming model as kmdf, but it uses different components, interfaces, and data structures. for example, kmdf includes objects unique to kernel mode, while umdf includes some objects unique to user mode. objects and functionality that can’t be accessed through umdf include direct handling of interrupts, dma, nonpaged pool, and strict timing requirements. furthermore, a umdf driver can’t be on any kernel driver stack or be a client of another driver or the kernel itself .
in an implementation, the xks _ isr interface 114 may be implemented by a small shim in the user - mode framework reflector 108. the xks _ isr interface 114 may be responsible for watching for interrupt storms. an exemplary isr interface may be :
the splitter analyzes the device driver and determines how functions implemented in the driver must be split between kernel - mode and user - mode. it builds a static call - graph of the driver (including edges for indirect calls), identifies critical root functions, and classifies functions transitively called by them as critical, as described in the study in
umdf exposes the user mode device - driver interface (ddi). umdf is a dll of com - style objects that support the presentation, flow, and management of i / o and plug and play requests to the driver .
thus, an implementation to solve the contention may be to use a stop - and - go strategy where a device is initialized in non - interrupting state. when the user - mode driver receives transfer requests, it sets up one dma transfer including enabling interrupt for the dma transaction. the user - mode driver then waits on the interrupt event. at some point, interrupt occurs either due to error or completion of the transfer. the kernel mode isr dismisses and disables the interrupt, by reading and writing registers, and it signals the user mode isr which processes the result. the user - mode driver then can continue the next dma transfer if there is one. this serialization of isr and dma request eliminates the contention of accessing hardware registers and any shared resources .
a device driver includes a kernel mode and a user - mode module. the device driver may access device registers while operating in user - mode to promote system stability while providing a low - latency software response from the system upon interrupts. the device driver may include kernel stubs that are loaded into the operating system, and may be device specific code written. the stubs may be called by a reflector to handle exceptions caught by the stubs. a reset stub may be invoked by the reflector when the user - mode module or host terminates abruptly or detects an interrupt storm. the reset stub may also be invoked if errant dma operations are being performed by a hardware device. the reset stub may ensure that hardware immediately stops unfinished dma from further transfer, and may be called by the user - mode driver module .
all kmdf and umdf 2 drivers can use an always on, always available inflight trace recorder (ifr). when a driver provides a custom trace, the driver ifr log contains the trace messages. note that the new driver ifr log is separate from the framework ifr log that wdf creates for each driver .
i' m sure i noticed that when i installed wmp11 one of the install steps was registering the user - mode driver framework. or words to that affect. does this mean that the umdf can be taken downstream, or is the installer talking rubbish? (or me, it could be me talking rubbish )
the user - mode framework driver 101 may transfer data from a system to a device using dma, which is a capability provided by some computer bus architectures, including pci, pcmcia and cardbus, which allows data to be sent directly from an attached device to the memory on the host, freeing the cpu from involvement with the data transfer and thus improving the host' s performance. dma buffers 102 provide a memory where data is buffered as it is communicated to / from the user - mode framework driver 101. the dma buffers 102 may be allocated as a contiguous buffer or may be fragmented in the physical memory and mapped to a contiguous buffer in the calling process' s virtual address space. in some implementations, the dma buffers 102 may come from requests presented to the user - mode framework driver 101, in which case they may not need to be mapped into the address space of the host or even accessible directly to the stub .
i realise you probably cant tell me this which i can perfectly understand i mean its not optimised yet etc but... do you have any rough benchmarks at the moment comparing a user mode driver to kernel mode and if so what were the results and the device being testing? on a seperate note, sorry if this is mentioned elsewhere but will the user mode process run at a higher priority to normal apps ?
a device driver framework in a computing system may include a user - mode module, one or more kernel stubs including a reset stub, a shared memory to share information between the user - mode module and the kernel stubs, and a reflector to manage communication between the user - mode module, the kernel stubs, and an application. the kernel stubs may include code that is invoked as an interrupt service routine in response to an interrupt received from a device and write information from the device to the shared memory. the user - mode module may then read information from the shared memory. after executing the interrupt service routine, the kernel stub may hand off handling of the interrupt to the user - mode module. the kernel stub may be protected using a software - based fault isolation mechanism that monitors for exceptions such as an interrupt storm. upon detecting an interrupt storm, the reset stub may stop a hardware device from generating the interrupts to maintain system stability. the kernel stubs may synchronize with the interrupt service routine and / or user - mode module using a deferred procedure call .
safe device driver model based on kernel - mode jvm
, chen et al. , 2007, pages 1 - 8
3. checking and dismissing interrupts may take a read and a write to the registers for most hardware. therefore, it is non - atomic. if drivers set up dma in user - mode, which has to manipulate hardware registers, there may be contention between isr and the user - mode code .
three factors lead us to believe that implementing non - critical functionality as a user - mode process will also improve system reliability and availability as a whole .
the driver manager is a windows service that manages all instances of the wudfhost driver host process. the driver manager launches and tracks information about each driver host process. each host is a child process of the driver manager. only one driver manager exists per system. the driver manager starts during installation of the first umdf device and runs on the system thereafter .
the code generator uses the critical functions identified and emits code for the kernel - mode and user - mode components. it also generates all the code to handle upcalls and downcalls, including stubs and code to marshal / unmarshal data structures. the object tracker and threadpool implementation (for the multithreaded user - mode component) are common to all microdrivers and need to be written just once .
] report user - mode driver performance comparable to in - kernel device drivers. however, unlike microdrivers, they require both kernel support, and rewriting device drivers, making them incompatible with existing operating systems .
of course, microdrivers are not a panacea for device driver reliability problems. a bug in the kernel - mode component of a microdriver could still crash the operating system. it is also possible that by splitting functionality between a user - mode and kernel - mode component, microdrivers can expose otherwise latent bugs. for example, a latent race condition in a device driver could potentially be exposed in its microdriver implementation .
commodity operating systems achieve good performance by running device drivers in - kernel. unfortunately, this architecture offers poor fault isolation. this paper introduces microdrivers, which reduce the amount of driver code running in the kernel by splitting driver functionality between a small kernel - mode component and a larger user - mode component. this paper presents the microdriver architecture and techniques to refactor existing device drivers into microdrivers, achieving most of the benefits of user - mode drivers with the performance of kernel - mode drivers. experiments on a network driver show that 75% of its code can be removed from the kernel without affecting common - case performance .
the kernel stubs may be untrusted, while executing safely in the kernel because of a software based fault isolation mechanism 107, such as xfi, that allows user - mode framework drivers to add kernel stub to the kernel without possibly corrupting the integrity of the kernel itself, or its subsystems .
in addition to the wudfhost process hosting your driver, there is another user mode process that' s part of the umdf
system .
the second process is the umdf driver manager service that communicates with the wudfhost process running your driver and any other wudfhost processes running on the system. this service, which is started as part of starting the device, is responsible for host process lifetimes and responding to messages from the umdf kernel mode reflector driver .
umdf drivers run in a driver host process, which runs in the security credentials of a localservice account, although the host process itself is not a windows service. thus, user - mode drivers are as secure as any other user - mode service. when a umdf driver issues i / o requests, it can optionally impersonate its client process. impersonation enables the driver thread to run in the security context of the client so that the system performs access checks against the client' s identity rather than that of the driver host process .
before writing a driver—even a user mode driver—you must understand the basics of the windows i / o architecture, as shown in figure 1. in this overview, we will discuss some of the major principles behind the i / o system and define the most important terms .
before writing a user mode driver you must understand the basics of the umdf architecture. ron reeves, author of windows 7 device driver, looks at the overall block diagram of the umdf, and at the major activity: the i / o flow for the umdf .
unlike kmdf drivers, which run as driver objects representing a. sys image file, umdf drivers run in a driver host process, similar to a service - hosting process. the host process contains the driver itself (which is implemented as an in - process com component), the user - mode driver framework (implemented as a dll containing com - like components for each umdf object), and a run - time environment (responsible for i / o dispatching, driver loading, device - stack management, communication with the kernel, and a thread pool) .
], synchronizes copies of a data structure in the kernel' s address space and the user - mode process' address space. it has three main functions .
several enhancements are possible to the basic architecture of a microdriver. functions that are repeatedly called from both the kernel - mode component and user - mode component can potentially be replicated in both components, thus avoiding the overhead of an address - space change each time the function is accessed. similarly, a frequently - accessed data structure can be allocated in a shared memory region that is accessible both to the kernel and the user - mode process. finally, to ensure fast operation of the user - mode process, the operating system can pin the process' pages to memory .
the host process is the process in which the user mode driver runs. the host process is a child process of the driver manager and runs in the security credentials of a localservice account, although it is not a windows service. the host process includes the following components :
by default, if the objectsforleakdetection key is not specified, the framework monitors wdfrequest, wdfworkitem, wdfkey, wdfstring, wdfobject, and wdfdevice .
], and is an important motivation for microkernels. this has resulted in several services, that were previously implemented in the kernel, being implemented in user - mode (
kernel - mode drivers if specific kernel support for a device that is managed by a umdf driver is needed, it is also possible to write a companion kernel - mode driver that fills that role. in this way, it is possible for a device to be managed both by a umdf and a kmdf (or wdm) driver .
3. handling of level triggered interrupts that are not shared. this mechanism may be implemented with a minimal amount of kernel - mode code. if the interrupt is not shared, then the interrupt handler may mask the interrupt at the interrupt controller (effectively blocking it) and notify the user - mode driver to handle the device. the user - mode driver code may make a request to the system (reflector, etc .) at the end of processing that unmasks the interrupt line, at which point a new interrupt may come in .
first, fault isolation improves. any bugs that crash the user - mode process of a microdriver will potentially render the corresponding device unusable but will not affect the rest of the operating system. the device driver can then be restarted in isolation to restore operation of the device. note that because the kernel - mode component of a microdriver implements critical device functionality, such as interrupt processing, it is possible to keep the device operational even if the user - mode process crashes. for example, the kernel - mode component can implement error - checking code that detects that the user - mode process has crashed, and wait until the process restarts. however, as it does so, it can still serve other requests to / from the device .
to determine the version of the library that your driver is running with, the driver can call wdfdriverisversionavailable or wdfdriverretrieveversionstring .
]. second, switching between the kernel and a user - mode device driver involves the costly overhead of changing protection domains. for devices such as high - throughput network cards, this can result in significant latencies and performance penalties [
2. interrupt information is reflected in completed buffers or in a hardware register set which is manipulated by user mode code which may synchronize among multiple threads that access hardware registers .
the reflector is a kernel - mode driver that permits an application and a driver host process (and user - mode device stacks) to communicate. the reflector creates a separate device object for each device instance and handles plug and play (pnp) and power i / o requests associated with each device instance. all communication between the application and the driver host process happens through the reflector. for more information, see architecture of umdf .
the host process is the process in which the user mode driver runs. it is separate from the application process and the driver manager. it runs in the security credentials of a localservice account, although it is not a windows service. the host process contains the user mode device stack for the device. the device stack is visible to all applications across the system. each instance of a device has its own device stack. currently each instance has a separate driver host process, too. the host process includes the following components :
umdf is a new way of allowing drivers that support protocol bus based devices (initially just usb) to be written in user mode. the types of devices currently supported are :
second, because the kernel - mode component of the microdriver implements critical and heavily - used functionality, this code is likely more heavily tested than the user - mode component. further, because the kernel - mode component is a relatively small entity, it can either be verified, subject to thorough code audits, or be protected with mechanisms such as sfi [
to achieve this goal, the framework is designed to work with drivers on an
opt - in
basis. when you write a umdf driver, you provide callback routines for only the events that affect your device. for example, some devices require intervention immediately after they are turned on and just before they are turned off. the driver for such a device can implement callback functions that the framework calls at those times .
the user - mode framework driver 101 may operate as part of a stack of drivers that manage a hardware device. in an implementation, to provide for hardware that requires a low - latency response, the user - mode framework driver 101 may include kernel stubs loaded into the operating system, and may be device specific code written by, e. g. , hardware vendors. the kernel stubs may be provided to handle outstanding dma transfers and to provide better performance. the stubs are called by a reflector 108 via xkd _ ddi 112. the reflector 108 contains code to handle exceptions in stubs caught by sfi 107. the following kernel - mode stubs may be implemented: stub _ reset 105 (reset), stub _ isr 106 (isr) and stub _ syncexe 109 (syncexe). these three stubs execute at dirql with the interrupt spinlock, hence synchronization is provided for.
user-mode driver framework ( umdf ) is a device-driver development platform first introduced with microsoft 's windows vista operating system , and is also available for windows xp . it facilitates the creation of drivers for certain classes of devices . 
user-mode driver framework (umdf) is a device-driver development platform first introduced with microsoft's windows vista operating system, and is also available for windows xp. it facilitates the creation of drivers for certain classes of devices.
user-mode driver framework (umdf) is a device-driver development platform first introduced with microsoft's windows vista operating system, and is also available for windows xp. it facilitates the creation of drivers for certain classes of devices.