1. Using the Windows Driver Framework to build better drivers
HW-328T
Using the Windows Driver Framework to build better drivers
Peter Wieland
WDF Team Technical Lead
Microsoft Corporation
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

2. Agenda Types of drivers in Windows
Challenges to writing a quality driver
How the Windows driver framework (WDF) helps
Takeaways
Know how the WDF will help you deliver a great driver for a great customer experience

3. Your customers won’t notice a great device driver
, but they’ll certainly notice if it isn’t.
Your customers won’t notice a great device driver

4. Types of driver models Full Driver I/O Handling Plug & Play Power
Talking to HW
Boilerplate
Programming Device
Class Driver
I/O Handling
Plug & Play
Power
Talking to HW
Boilerplate
Programming Device
Driver Code
Microsoft Code
Mini Driver
I/O Handling
Talking to HW
Boilerplate
Programming Device
Miniport Driver
I/O Handling
Plug & Play
Power
Talking to HW
Boilerplate
Programming Device
Power
Plug & Play

5. Anatomy of a full Windows driver
Windows Driver Model (WDM)
Driver Code
Microsoft Code
I/O Handling
Power
Plug & Play
Boilerplate
Driver
Programming Device
Talking to Hardware
Hardware (or another driver)
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

6. Anatomy of a WDF driver Windows Driver Model (WDM) I/O Handling Power
Driver Code
Microsoft Code
I/O Handling
Power
Plug & Play
Boilerplate
Driver
Programming Device
Talking to Hardware
Hardware (or another driver)
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

7. WDF for kernel mode drivers
Kernel Mode Framework (KMDF) provides
Composable building blocks
Default behaviors
Consistent interfaces & development patterns
Start simple, opt into complexity as required
WDF doesn’t wrap everything
Interfaces focus on common driver scenarios
Can escape to WDM if needed

8. WDF for user mode drivers
User Mode Host
User Mode Framework (UMDF) is most of KMDF but in user-mode
Simpler, more familiar development environment for new driver developers
User is isolated from driver crashes or security breaches
Developer is isolated from crashes too
Supported for many peripheral devices
I/O Handling
Power
Plug & Play
Device Specific Code
(i.e. Driver)
Talking to Hardware
Kernel
WDM
Hardware

9. A simple little driver

10. Simple little driver Fully functional driver Full Plug & Play support
Could install this on any USB device
Full Plug & Play support
Full power management
Written using KMDF

11. SimpleLittleDriver.sys #include <wdk.h> #include <wdf.h>
DRIVER_INITIALIZE DriverEntry;
EVT_WDF_DRIVER_DEVICE_ADD OnDeviceAdd;
NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject,
PUNICODE_STRING RegistryPath) {
WDF_DRIVER_CONFIG config;
WDF_DRIVER_CONFIG_INIT(&config, OnDeviceAdd);
return WdfDriverCreate(DriverObject,
RegistryPath,
WDF_NO_OBJECT_ATTRIBUTES,
&config,
WDF_NO_HANDLE); }
NTSTATUS OnDeviceAdd(WDFDRIVER Driver,
PWDFDEVICE_INIT DeviceInit) {
return WdfDeviceCreate(&DeviceInit,
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

12. SimpleLittleDriver.sys Called when driver loads #include <wdk.h>
#include <wdf.h>
DRIVER_INITIALIZE DriverEntry;
EVT_WDF_DRIVER_DEVICE_ADD OnDeviceAdd;
NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject,
PUNICODE_STRING RegistryPath) {
WDF_DRIVER_CONFIG config;
WDF_DRIVER_CONFIG_INIT(&config, OnDeviceAdd);
return WdfDriverCreate(DriverObject,
RegistryPath,
WDF_NO_OBJECT_ATTRIBUTES,
&config,
WDF_NO_HANDLE); }
NTSTATUS OnDeviceAdd(WDFDRIVER Driver,
PWDFDEVICE_INIT DeviceInit) {
return WdfDeviceCreate(&DeviceInit,
Called when driver loads
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

13. SimpleLittleDriver.sys
#include <wdk.h>
#include <wdf.h>
DRIVER_INITIALIZE DriverEntry;
EVT_WDF_DRIVER_DEVICE_ADD OnDeviceAdd;
NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject,
PUNICODE_STRING RegistryPath) {
WDF_DRIVER_CONFIG config;
WDF_DRIVER_CONFIG_INIT(&config, OnDeviceAdd);
return WdfDriverCreate(DriverObject,
RegistryPath,
WDF_NO_OBJECT_ATTRIBUTES,
&config,
WDF_NO_HANDLE); }
NTSTATUS OnDeviceAdd(WDFDRIVER Driver,
PWDFDEVICE_INIT DeviceInit) {
return WdfDeviceCreate(&DeviceInit,
Callback for when driver is attached to a device
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

14. SimpleLittleDriver.sys Use configuration to make a “driver object”
#include <wdk.h>
#include <wdf.h>
DRIVER_INITIALIZE DriverEntry;
EVT_WDF_DRIVER_DEVICE_ADD OnDeviceAdd;
NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject,
PUNICODE_STRING RegistryPath) {
WDF_DRIVER_CONFIG config;
WDF_DRIVER_CONFIG_INIT(&config, OnDeviceAdd);
return WdfDriverCreate(DriverObject,
RegistryPath,
WDF_NO_OBJECT_ATTRIBUTES,
&config,
WDF_NO_HANDLE); }
NTSTATUS OnDeviceAdd(WDFDRIVER Driver,
PWDFDEVICE_INIT DeviceInit) {
return WdfDeviceCreate(&DeviceInit,
Use configuration to make a “driver object”
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

15. SimpleLittleDriver.sys
#include <wdk.h>
#include <wdf.h>
DRIVER_INITIALIZE DriverEntry;
EVT_WDF_DRIVER_DEVICE_ADD OnDeviceAdd;
NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject,
PUNICODE_STRING RegistryPath) {
WDF_DRIVER_CONFIG config;
WDF_DRIVER_CONFIG_INIT(&config, OnDeviceAdd);
return WdfDriverCreate(DriverObject,
RegistryPath,
WDF_NO_OBJECT_ATTRIBUTES,
&config,
WDF_NO_HANDLE); }
NTSTATUS OnDeviceAdd(WDFDRIVER Driver,
PWDFDEVICE_INIT DeviceInit) {
return WdfDeviceCreate(&DeviceInit,
Callback when Windows assigns the driver to a device
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

16. SimpleLittleDriver.sys
#include <wdk.h>
#include <wdf.h>
DRIVER_INITIALIZE DriverEntry;
EVT_WDF_DRIVER_DEVICE_ADD OnDeviceAdd;
NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject,
PUNICODE_STRING RegistryPath) {
WDF_DRIVER_CONFIG config;
WDF_DRIVER_CONFIG_INIT(&config, OnDeviceAdd);
return WdfDriverCreate(DriverObject,
RegistryPath,
WDF_NO_OBJECT_ATTRIBUTES,
&config,
WDF_NO_HANDLE); }
NTSTATUS OnDeviceAdd(WDFDRIVER Driver,
PWDFDEVICE_INIT DeviceInit) {
return WdfDeviceCreate(&DeviceInit,
Create a “Device Object” for this driver and add it to the driver stack
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

17. SimpleLittleDriver.sys Less than 25 lines of code Minimal boilerplate
Minimal cleanup code
#include <wdk.h>
#include <wdf.h>
DRIVER_INITIALIZE DriverEntry;
EVT_WDF_DRIVER_DEVICE_ADD OnDeviceAdd;
NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject,
PUNICODE_STRING RegistryPath) {
WDF_DRIVER_CONFIG config;
WDF_DRIVER_CONFIG_INIT(&config, OnDeviceAdd);
return WdfDriverCreate(DriverObject,
RegistryPath,
WDF_NO_OBJECT_ATTRIBUTES,
&config,
WDF_NO_HANDLE); }
NTSTATUS OnDeviceAdd(WDFDRIVER Driver,
PWDFDEVICE_INIT DeviceInit) {
return WdfDeviceCreate(&DeviceInit,
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

18. Storing Driver Specific Data

19. Tracking memory use
Drivers are very dynamic, lots of state to track & cleanup
State of device, client requests, background work, etc…
Error handling adds to clean-up work
Becomes difficult to keep up with
Drivers share address space
Proper management is critical
WDF automates much of this through objects

20. WDF objects WDF objects help driver manage its state & allocations
WDF objects make up the WDF API
WDF knows the lifetime of many objects, deletes automatically
Object context
Space for driver to store its own data
Freed with the object
Object events to help with clean-up
Object parents & children
Can override default object parent
Deleting an object deletes the children

21. Adding Driver’s State & Data
Define a structure to hold driver’s private data for the Device
struct DeviceContext {
MYDEVICE_STATE CurrentState;
... };
WDF_DECLARE_CONTEXT_TYPE_WITH_NAME(DeviceContext,
GetDeviceContext);
NTSTATUS OnDeviceAdd(...) {
WDFDEVICE device;
DeviceContext* context;
WDF_OBJECT_ATTRIBUTES attributes;
WDF_OBJECT_ATTRIBUTES_INIT_CONTEXT_TYPE(&attributes,
DeviceContext);
attributes.EvtDestroyCallback = OnDeviceDestroy;
WdfDeviceCreate(&DeviceInit, &attributes, &device);
if (failure) {return status;}
deviceContext = GetDeviceContext(device);
deviceContext->CurrentState = MyDeviceStateUninitialized; }
Declare the structure to be an object context type. GetDeviceContext will get it from the object
Initialize object attributes structure with the new context type
Set a callback to free memory allocated for the device
Supply object attributes when creating device
Get the context off the new object & initialize it
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

22. Creating Child Objects
NTSTATUS OnDeviceAdd(...) {
WdfUsbTargetCreate(device,
WDF_NO_OBJECT_ATTRIBUTES,
&deviceContext->UsbIoTarget);
if (failure) return status;
WDF_OBJECT_ATTRIBUTES attributes;
WDF_OBJECT_ATTRIBUTES_INIT_CONTEXT_TYPE(&attributes,
RequestContext);
attributes.ParentObject = deviceContext->UsbIoTarget;
WdfRequestCreate(&attributes,
deviceContext->UsbIoTarget,
&deviceContext->UsbRequest);
InitializeRequestContext(deviceContext->UsbRequest);
... }
WDF deletes Driver and Device Objects automatically on failure or during removal/unload
Which deletes the USB Target
Which deletes the Request
Make a USB Target as a child of the device (default parent)
Make a Request as a child of the USB Target
Create Request
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

23. Handling I/O

24. Handling I/O operations
Clients can open SimpleLittleDriver but can’t send I/O
SimpleLittleDriver doesn’t register any I/O handlers
Challenges for I/O handling are:
Asynchronous execution
Concurrency
Validation
Cancellation
Clean-up
WDF drivers handle I/O with queue and request objects

25. I/O queues Queues coordinate flow of requests within the driver
Driver can use multiple queues to collect or distribute work
Can dispatch requests one at a time or in parallel
WDF presents all I/O through the top level queues
Can use queues as gates to stop and restart I/O flow

26. Request objects Packets of work from a client
Packets support asynchronous I/O
Driver can add context/children to track state & clean-up
Simplify validation of parameters/payload
Help manage race conditions between delivery, cancellation & completion

27. Registering an I/O Callback
NTSTATUS OnDeviceAdd(…, PWDFDEVICE_INIT DeviceInit) {
...
// After creating the device…
WDF_IO_QUEUE_CONFIG queueConfig;
WDF_IO_QUEUE_CONFIG_INIT_DEFAULT_QUEUE(
&queueConfig,
WdfIoQueueDispatchSequential );
queueConfig.EvtIoDeviceControl = OnDeviceControl;
WdfIoQueueCreate(device,
WDF_NO_OBJECT_ATTRIBUTES,
WDF_NO_OBJECT); … }
Creating an I/O Queue starts with the Object configuration
Make this the device’s default Queue
Dispatch requests one at a time
Add handler for device control Requests
Create the Queue (child of Device)
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

28. Device Control Handler
Handler for a device-specific operation (aka I/O control or IOCTL)
VOID OnDeviceControl(WDFQUEUE Queue, WDFREQUEST Request,
size_t InputCb, size_t OutputCb,
ULONG IoControlCode) {
if (IoControlCode != IOCTL_MYDRIVER_DO_SOMETHING) {
goto error; }
WdfRequestRetrieveInputBuffer(Request,
sizeof(DO_SOMETHING_INPUT),
&input,
NULL);
if (failure) goto error;
// Validate input structure
// Start request running.
return;
Error:
WdfRequestComplete(Request, status);
Device only supports one IOCTL
Get the input buffer, which contains parameters from the client
Require input to be at least this size (simplifies validation)
Make sure all the input parameters are valid.
Kick off the request processing asynchronously (for very short requests, work can be done synchronously)
Complete the request on any errors. Request completion will trigger deletion.
Return the thread to the client. Some async callback later will trigger request completion.
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

29. Handling concurrency Use queues to serialize requests
Use parallel queues to distribute work to sub-queues
Use sequential/manual queues to collect work & protect shared resources (hardware, data, etc…)
Use locks to coordinate between I/O and other work
WaitLock or SpinLock Objects, or WdfObjectLock method
Limit blocking (including locks) in I/O paths
Ties up client’s threads & increases system latency

30. Power Management

31. Saving power
Power management is critical for that great user experience
Windows rules for power are very complicated
Must be coordinated with PnP and asynchronous I/O
Many drivers do it wrong
Don’t power off when they aren’t in use, or
Don’t handle all the edge cases or concurrency
10% of all driver crashes are related to power management

32. Enabling power management
When creating a device, WDF driver
Declares device’s power capabilities
Sets power event callbacks
WDF’s power state machines control power automatically
Handles OS power change requests
Calls driver to perform device-specific power actions
Power on, power off, arm for wake, etc…

33. Detecting need for power
Driver can set queue’s PowerManaged attribute
Power-managed queues coordinate I/O and power for you
Holds requests until device is on
Starts power up sequence when new requests arrive
Use power managed queues when you touch hardware

34. Automatic idle detection
WDF can turn off idle devices automatically
Driver sets S0-Idle settings on device
Power state to enter
Timeout
Wake capability
System vs. driver managed transitions
Device is idle when all power managed queues are idle
Driver can stop and restart idle detection
To stay on when doing non request based work

35. Power Callbacks & Idle Settings
NTSTATUS OnDeviceAdd(...) { …
WDF_PNPPOWER_EVENT_CALLBACKS powerCb;
WDF_PNPPOWER_EVENT_CALLBACKS_INIT(&powerCb);
powerCb.EvtDeviceD0Entry = OnD0Entry;
powerCb.EvtDeviceD0Exit = OnD0Exit;
WdfDeviceInitSetPnpPowerEventCallbacks(DeviceInit,
&powerCb);
// create the device ...
WDF_DEVICE_POWER_POLICY_IDLE_SETTINGS idleSettings;
WDF_DEVICE_POWER_POLICY_IDLE_SETTINGS_INIT(
&idleSettings,
IdleUsbSelectiveSuspend );
idleSettings.IdleTimeout = 500; // milliseconds
WdfDeviceAssignS0IdleSettings(device, &idleSettings);
if (failure) return status; }
Driver can set PnP/Power callbacks to customize device startup, shutdown & power behaviors
OnD0Entry will turn the device on, restore any volatile settings
OnD0Exit saves the current state of the device and turns it off
Set power callbacks before creating the Device
After creating the device, setup the idle policy using USB selective suspend to wake (since this is a pretend USB devcice)
Driver can override WDF’s default timeout
Setup behavior of device when idle in system working state (S0)
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

36. Summary

37. Windows driver frameworks
WDF lets you focus on controlling your device, not dealing with the OS
KMDF can significantly reduce driver size and complexity
UMDF provide a more familiar development environment
Both let you build a high-quality driver quickly

38. What type of driver do I need?
Use Windows class drivers where possible
Follow driver model for your device class
Use WDF’s support objects in “miniport mode” as-needed
For full drivers, use UMDF where possible
Use KMDF everywhere else
You should never have to write a WDM driver

39. Your customers won’t notice a great device driver, but they’ll certainly notice if it isn’t.

40. Related sessions [HW-773T] Building great USB 3.0 devices
[HW-322T] Designing great devices and drivers
[HW-235T] Developing drivers in Visual Studio
[HW-907C] Inside the Windows 8 driver developer workflow
[HW-721H] Experiencing Windows Driver Kit integration with Visual Studio

41. Further reading and documentation
Getting Started:
The WDF Book: Developing Drivers with Windows Driver Foundation by Orwick and Smith
50% off coupon code DDWDF
Kernel-Mode Driver Framework Design Guide
User-Mode Driver Framework Design Guide
Choosing a driver model
What’s New in Windows Driver Frameworks for Windows 8
Contact info –
Blogs - Mine, and others about WDF

42. thank you Feedback and questions http://forums.dev.windows.com
Session feedback

43. 4/20/2017 2:39 AM
© 2011 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.
© 2011 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.