Mobile Broadband Driver Development for Windows 7

Malayala Srinivasan (Srini)Senior Program Manager LeadWireless WAN - Microsoft IDC r.malayala.srinivasan@microsoft.com

Agenda

• Session Goals

• Mobile Broadband in Windows 7

• Driver Design Challenges

• Driver Development Stages

• Call to Action

Session Goals

• This session is targeted for the Mobile Broadband driver developer community and will:

• Introduce Mobile Broadband (MB) driver development for

Windows 7

• Identify and prepare for key driver design areas in Windows 7

• Help in getting ready for MB driver development in Windows 7

Terminology

• Mobile Broadband is also referred as • Wireless WAN• WWAN• MB

• VAN UI – View Available Networks UI is• Windows Vista’s “Connect to network” UI equivalent in

Windows 7• Launched either through “Connect To” or “Network Tray Icon”

• Mobile Broadband Driver is also referred as• IHV Miniport Driver• MB Driver• Miniport Driver

Mobile Broadband in Windows 7

• Driver developers must use the “Mobile Broadband Driver Model Specification” for Windows 7

• Supports packet-switched data connectivity over the Wireless WAN (3GPP / 3GPP2) devices

• Based on NDIS6.20 miniport driver model

• Control path designed for slow response devices (AT command based)

• Data path optimized for Wireless WAN devices

• New logo program for Mobile Broadband devices in Windows 7

• New APIs for Mobile Broadband user-mode application development in Windows 7

WWAN Miniport Driver

NDISUIO

Windows 7 Mobile Broadband Architecture

Provided by:

Microsoft

ISV

OEM

IHV

3rd Party Connection Manager

WWAN Service Profiles

WWAN Miniport DriverMB Miniport Driver

Use

r Mod

eKe

rnel

Mod

e

Mobile Broadband Driver Model

Mobile Broadband Driver Model

Command Line Interface

Command Line Interface

Mobile Broadband API

View Available Network UI Properties UI Connection Flow

Experience UI

Sess

ion

0

NDIS6.20 Data Path Optimizations for MB Devices

IHV Miniport Driver

NDIS 6.0

TCP/IP Stack

Send / Receive

802.3 Frames

NDIS 6.20

TCP/IP Stack

IHV Miniport Driver

Send / Receive

IP Frames

DHCP EmulationARP Emulation

Windows Vista Windows 7

Windows 7 IHV Miniport Drivers for Mobile Broadband can:• Take advantage of raw IP support in send/receive path• Eliminate DHCP and ARP spoofing in miniport drivers

Control Path Functionalities

• Mobile Broadband Driver Model defines the following control path functionalities for the IHV drivers

• Device State Management• Connectivity Management• Radio Control• SMS (Short Message Services)• PIN• Provisioned Contexts • Service Activation• Vendor Specific

Control Path for Mobile Broadband Drivers

• WWAN Service uses NDIS OIDs for control requests (SET or QUERY) to miniport drivers.

• Miniport drivers can respond asynchronously to WWAN Service.

• Device state changes can be notified to WWAN service using event notification by miniport drivers

Asynchronous Response

• Designed for slow responding AT command based devices

• Initiated by WWAN Service

• 2 Types : SET or QUERY

• RequestId is Non-NULL

WWAN Service

Miniport Driver

NdisOidRequest

Oid = OID_WWAN_CONNECTRequestHandle = 0x12345678

RequestId = 0x0000F00D…

Return

NDIS_STATUS_INDICATION_REQUIRED

NdisMIndicateStatusEx

StatusCode = NDIS_STATUS_WWAN_CONTEXT_STATE

DestinationHandle = 0x12345678RequestId = 0x0000F00D

ActivationState = WwanActivationStateActivated …

Device Responds

AT Cmd(s) to Device

Event Notification

• Used for device or network state changes

• Initiated by driver

• Request Id = NULL

WWAN Service

Miniport Driver

NdisMIndicateStatusEx

StatusCode = NDIS_STATUS_WWAN_CONTEXT_STATE

RequestId = 0x0ActivationState =

WwanActivationStateDeactivated …

Device / Networkstate change

MB Miniport Driver

WWAN Service

Custom IHV Features

• Framework provides vendor-specific OID for driver developers to implement IHV specific features

• WWAN Service provides a pass-through control path for Windows 7 applications to communicate with IHV drivers

3rd Party Apps / Connection Managers

OID

_WW

AN_V

END

OR_

SPEC

IFIC

ND

IS_S

TATU

S_W

WAN

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VEN

DO

R_SP

ECIF

IC

Set V

endo

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vent

Noti

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Driver Design Challenges

OID Handler Implementation

• Understand AT commands and response from device.

• Responding to each OID may require sending multiple AT commands to device.

• Incorrect string processing in kernel mode may result in fatal failures. • See “Using Safe String Functions” in the WDK

http://msdn.microsoft.com/en-us/library/aa489552.aspx

• Partner with your Connection Manager application developer or firmware engineer to get more insight on AT command semantics.

• Some OID requests may require using device-specific AT commands.

• Some OID responses (e.g, network error code, service activation, and raw IP handling) may require firmware changes. Partner with your device firmware team to get firmware changed.

Asynchronous OID Handling

• WWAN Service may send multiple OIDs without waiting for the completion of the current OID request.

• Driver developers should design query OID handlers to send the requests to the device without serializing.

• For out-of-sequence device responses, use command tag in the response to associate the response with the corresponding request.

IHV and Operator-specific Commands

• Use OID_WWAN_VENDOR_SPECIFIC to implement custom features. For example: • SIM Tool Kit (STK) Commands• USSD Commands• Phonebook Commands• Voice Commands• Firmware-specific commands• And more …

• Use OID_WWAN_SERVICE_ACTIVATION to implement operator-specific service activation.

Staged Driver Development

Stage 0•Develop NDIS 6.0 driver or migrate from NDIS 5.x to NDIS 6.0 , if available•Use custom Connect / Disconnect Control OID•Test Send/Receive Path

Stage 1•Implement basic OIDs from MB Driver Model Spec.*•Test Connect / Disconnect experience with Windows 7 “VAN UI”•Make the AT command parsing implementation robust

Stage 2•Design and implement concurrent OID request handler.•Implement rest of the mandatory OIDs from MB Driver Model spec•Test PIN, roaming and profile related experience with Windows 7 UIs

Stage 3•Data Path: Migrate to NDIS 6.20 - Implement Raw IP support. Remove DHCP & ARP•Use MB Logo tests to find issues and fix them•Prepare for Mobile Broadband Device Logo

Driver Test Tools

Use existing Connection Manager Write simple connect /

disconnect app.

WwanDriverTestApp from WDK * Windows 7 VAN UI , Advance UI *

WwanDriverTestApp from WDK Windows 7 VAN UI , Advance UI Mobile Broadband Logo Tests

from WLK

WwanDriverTestApp from WDK Windows 7 VAN UI , Advance UI Mobile Broadband Logo Tests

from WLK

High Level TasksStage

* Available at the time of Windows 7 Beta

Test the driver in each stage

Development Best Practices

• Plan and implement the following items early in the development cycle of a Mobile Broadband driver :

• Log the AT commands and responses in a file. Helps in debugging and root cause analysis.

• Use Event Tracing to log configuration and network issues.• NdisWriteErrorLogEntry DDI for logging driver-related errors• NdisWriteEventLogEntry DDI for logging generic or network-related

issues • Use the optional description member “StringsList” to log meaningful and

actionable information regarding the error.

Call To Action

• Migrate existing NDIS 5.x mobile broadband drivers to NDIS 6.0• Helps in moving to NDIS 6.20-based Mobile Broadband Miniport model.• MB devices must be NDIS 6.20-based to get logo.

• Prepare for testing commercially deployed Mobile Broadband device solutions in Windows 7.

• Get ready for Windows 7-based driver development.• WDK will be available at the time of Windows 7 Beta.

• Review Mobile Broadband device logo requirements and send us feedback.

• Contact us at win7mb@microsoft.com

Resources• Mobile Broadband Logo Requirements on https://winqual.microsoft.com/

• Log in, click on the Logopoint link on the left side menu, and search for “MBN” requirements.

• WDK Documentation on MSDN• Porting NDIS 5.x Drivers to NDIS 6.0

http://msdn.microsoft.com/hi-in/library/ms795567(en-us).aspx• IP Helper

http://msdn.microsoft.com/hi-in/library/bb742902(en-us).aspx

• Check the Windows 7 Beta release for additional resources:• WDK documentation

• Mobile Broadband Driver Model Specification• Mobile Broadband Driver Test App (WwanDriverTestApp)• NDIS 6.20

• SDK documentation• Mobile Broadband API Specification

• Windows Logo Kit (WLK) • Mobile Broadband Logo Tests

• WHDC Web site at http://www.microsoft.com/whdc/default.mspx• Mobile Broadband Driver Development White Paper

Related SessionsSession Day / Time

NDIS 6.20 Overview Mon. 9:45-10:45 and Tues. 9:45-10:45

Unified Tracing and Network Diagnostics Framework Mon. 1:30-2:30 andWed. 11-12

Network Power Management in Windows 7 Tue. 5:15-6:15

Windows Logo Program Tests for NDIS Mon. 11-12Wed. 9:45-10:45

Lab: How to Debug an NDIS 6.20 Driver Mon. 2:45-3:45 and Wed. 9:45-10:45

Discussion: Porting Drivers to NDIS 6.20 Wed. 8:30-9:30

Extending Device Installation by Using Co-installers Mon. 4-5 andWed. 1:30-2:30

Using the Windows Feedback Loop to Deliver High-Quality Drivers Mon. 8:30-9:30 andWed. 8:30-9:30

Thank You!