Network Driver Interface Specification (NDIS) in Microsoft Windows CE 3.0
Summary: The objective of this white paper is to provide an overview of the Network Driver Interface Specification (NDIS) architecture in Microsoft® Windows® CE and the relevant information to write NDIS drivers for Windows CE. For the most part, this may indeed involve porting an NDIS Miniport driver from Windows NT® to Windows CE operating system. This paper starts with a brief introduction to NDIS, and then moves onto describing the support for NDIS in Windows CE and the details of writing an NDIS Miniport driver. (14 printed pages)
At the outset, the reader should note that the Microsoft Windows CE NDIS implementation is a subset of NDIS 4.0 implementation used in Windows NT operating system. Hence, you should consult the Microsoft Windows NT version 4.0 Driver Development Kit for complete documentation on NDIS architecture and all network connectivity issues. The documentation in the Windows CE Driver Development Kit only supplements the Windows NT documentation. This white paper references the documentation in both these toolkits.
NDIS on Windows NT
NDIS describes the interface by which one or more Network Interface Card (NIC) drivers communicate with one or more underlying network interface cards, with one or more overlying protocol drivers, and with the operating system. NDIS defines a fully abstracted environment for NIC driver development. For every external function that a NIC driver needs to perform, it can rely on NDIS routines to perform the operation. This includes the entire range of tasks performed by a NIC driver, from communicating with protocol drivers, to registering and intercepting NIC hardware interrupts, and communicating with underlying NICs by manipulating registers, port I/O, and so forth. Therefore, NIC drivers can be written entirely in platform-independent high-level languages such as C. These drivers can then be recompiled with a system-compatible compiler to run in any NDIS environment.
To provide this level of abstraction and portability, Windows NT provides an NDIS export library referred to here as the NDIS library or NDIS. All interactions between a NIC driver and protocol drivers, a NIC driver and the operating system, and a NIC driver and the network adapters that it controls are through calls to NDIS functions. NDIS is packaged in an export library as a set of functions, with emphasis on in-line macros for maximum performance. All NDIS drivers, including highest-level NDIS protocol drivers, intermediate NDIS drivers, and NIC drivers link against this library. When called, an NDIS function calls an associated function in a higher-level driver, in an intermediate NDIS driver, in a NIC driver, in the operating system, or else performs an internal-to-NDIS local action.
NDIS on Windows CE
As mentioned earlier, the NDIS implementation on Windows CE is a subset of the NDIS 4.0 implementation used on Windows NT. The differences between the Windows CE and Windows NT implementations are described later in this document. The complete NDIS specification supports several types of network drivers, but Windows CE version 2.0 and later only support writing NDIS Miniport drivers, not monolithic or full Network Interface Card (NIC) drivers.
For NDIS Miniport drivers, Windows CE is source code compatible with Windows NT. This means that, with a few exceptions, Windows CE and Windows NT support identical NDIS APIs. You can consult the Microsoft Windows NT Version 4.0 Driver Development Kit for full documentation regarding NDIS APIs and for extended information on how to write a Miniport driver. Although the documentation in Windows CE Driver Development Kit provides supplementary information pertaining to Windows CE NDIS Miniports, it does not discuss at length the process of writing Miniport drivers. This white paper tries to bridge that gap by providing as many details as possible on writing NDIS Miniport drivers. For a complete list of NDIS APIs supported by Windows CE, including documentation on the minor differences between Windows CE APIs and their Windows NT counterparts, consult the reference contained in this Windows CE Driver Development Kit.
Windows CE version 2.0 provided support for writing or porting Ethernet (802.3) Miniport drivers from Windows NT. Windows CE version 2.1 now supports writing or porting Windows NT IrDA Miniport drivers.
To summarize, here is a list of the key features of NDIS support in Windows CE.
- Portability of drivers between platforms supporting NDIS.
- Ethernet (802.3) and IrDA medium types.
- NDIS Miniport drivers only. Monolithic or full MAC drivers are not supported.
- A subset of Intermediate Miniport support. Intermediate Miniport/protocol drivers are not supported.
- Plug-and-Play loading of Miniport drivers for PC Card-based NICs.
- Can bind multiple Ethernet Miniport drivers to the TCP/IP protocol.
- One Miniport driver can manage multiple instances, i.e. NICs
Sample code on NDIS Miniports in Windows CE
There are several NDIS Miniport driver samples that are shipped in the Windows CE Embedded Toolkit and they are listed below. A driver developer should consult the following sample code to better understand the concept of writing an Ethernet or IrDA NDIS Miniport driver on Windows CE.
- NE2000 compatible PC Card/ISA Card/PCI Card Ethernet Miniport.
- Xircom CE2 PC Card Ethernet Miniport driver
- Proxim Wireless PC Card Ethernet Miniport driver
- IrSIR - Serial IR Intermediate Miniport driver with underlying serial driver
- National Semiconductor Fast IR Miniport driver for the NSC PC87338 chipset.
For example we provide an NE2000 sample that works with any NE2000-compatible network adapter. In Windows CE version 2.0, our NE2000 sample driver supported the PCMCIA bus, in Windows CE version 2.1 it supported the PCI bus, and in Windows CE version 2.11 it now supports the ISA bus. We have also added 3 more Miniport sample drivers in Windows CE version 2.1. A Proxim driver for Proxim wireless Ethernet PC Card devices, a Xircom driver for Xircom Ethernet PC Card devices, and a Fast IR driver for Fast IR network cards that are based on the National Semiconductor PC87338 chipset.
In addition, in Windows CE version 2.0, we shipped another sample driver namely the Serial IR Miniport driver - this driver is the only example of an Intermediate NDIS Miniport driver in Windows CE. In our internal testing at Microsoft, note that we have observed transfer rates of up to 4 MBps with our Fast IR driver and 115 KBps with our Serial IR driver, which is consistent with the Fast IR and Serial IR specifications. Another key point is that the IrDA protocol in Windows CE auto negotiates baud rates such that both Serial IR and Fast IR devices can inter-operate on the same device.
Figure 1 below shows an overview of the NDIS architecture in Windows CE. The NDIS architecture consists of several components:
- The NDIS wrapper component: Contained in NDIS.DLL file, this component provides the operating environment for drivers that use NDIS.
- Protocol Drivers: Windows CE supports two NDIS protocol drivers: TCP/IP and IrDA. These protocol drivers are exposed to applications via the Winsock application interface. Such a driver allocates packets, copies data from sending applications into packets, and sends these packets to the lower-level driver via the NDIS wrapper component. The protocol driver also provides a lower level interface (specified by NDIS) to receive incoming packets from the Miniport driver.
- NIC Miniport Drivers: NIC Miniports directly manage network interface cards. The NIC drivers interface through NDIS to the hardware at the lower edge and to upper layers at the upper edge to send packets, indicate received packets, reset the NIC, halt the NIC, and to query or set the operation characteristics of the driver.
- Intermediate Miniport Drivers: An intermediate miniport driver has the same upper edge interface as a NIC Miniport Driver. However, the lower edge instead interfaces with an underlying Driver Development, such as the serial driver.
Figure 1. NDIS Driver Architecture in Windows CE
Figure 2 below illustrates a more detailed Networking architecture in Windows CE, by using an example network configuration. There are two NDIS protocol drivers: TCP/IP and IrDA. Each protocol driver is bound to a single Miniport driver in this diagram. The IrDA protocol driver is bound to IrSIR -- the serial IR intermediate Miniport. The TCP/IP protocol driver is bound to an NE2000 Miniport driver. Windows CE does not support NDIS WAN, instead TCP/IP binds directly to the PPP component which interfaces directly with serial driver for modem and direct-cable connections.
Figure 2. Example networking configuration in Windows CE
Differences between Windows CE and Windows NT
There are several differences between Windows CE and Windows NT implementations of NDIS Miniports. This section highlights some of these differences.
- Even though the source code for Miniport drivers on Windows NT is compatible with Windows CE, the process of compiling a Miniport driver for Windows CE is slightly different from Windows NT. On Windows NT, Miniport drivers are compiled as system files (.sys). Windows CE, however, does not support system files, so you must compile the driver as a DLL instead. Because the driver is compiled as a DLL, it must export a function called DriverEntry in its .DEF file. Typically, this function performs any general initialization and then calls other functions in the DLL to perform platform-specific initializations. DriverEntry must have the following prototype.
NTSTATUS DriverEntry(IN PDRIVER_OBJECT pDriverObject, IN PUNICODE_STRING pRegistryPath);
For sample DriverEntry implementations, see the source code for the sample Miniport drivers provided in the Embedded Toolkit.
- Windows CE does not support .INF files for dynamic installation and configuration of NDIS Miniport drivers. For more information on installing NDIS drivers, please see the section on Installing and Binding NDIS Miniport drivers.
- Windows CE NDIS wrapper interface (NDIS.DLL) will never call the multi-packet send handler in the Miniport driver.
- Windows CE does not provide built-in support for DMA abstraction functionality. For further details on DMA, please refer to the DMA Considerations section below.
- Windows CE does not support allocating contiguous memory blocks from a Driver Development. Generally, contiguous memory is only required for DMA operations. For further details on DMA, please refer to the DMA Considerations section below.
- The I/O port address returned from NdisMRegisterIoPortRange is actually a 32-bit virtual address in Windows CE and should be treated as a 32-bit value. Windows CE does not use the lower 64K region of the I/O address space, so you should not use 16-bit values for I/O port addresses. Many Windows CE devices emulate I/O ports on top of mapped memory.
- The Windows CE implementation of NDIS does not provide access to the PCMCIA attribute memory. A driver must use PC Card Services functions in Windows CE to read the card tuple information. The Xircom CE2 sample driver that is in the Embedded Toolkit, contains examples of reading attribute space via PC Card Services.
Power Management Considerations
A Miniport driver on Windows CE must provide some additional code for Power Management considerations. These considerations are based on whether the network card is a PC Card NIC or built-in NIC.
- PC Card NICs. PC Card Services handles all power management for PC Card NDIS Miniports in Windows CE. This implies that the Windows CE Power-Down and Power-Up system events are transparent to NDIS Miniport drivers. Upon Power-Down to the system, PC Card Services maintains state information and disables power to the PC Card socket. Upon power resume to the system, PC Card Services issues a card-removal notification for all PC Card sockets with inserted cards. Then, the system checks the socket status and issues card-insertion notification for each socket with a card. What this means to a Miniport driver is that, upon Power-Up cycle, the driver is first unbounded and unloaded, and then reloaded and re-bound to the appropriate NDIS protocol.
In addition, note that a PC Card NIC may be removed at any time from the device, so the NDIS Miniport driver should have timeouts on all operations that poll the card's registers.
- Built-in NICs. For Built-in Miniport drivers, the system calls the Miniport driver's reset handler function upon a Power-Up event. The Miniport reset handler should issue a hardware reset to the peripheral and reset the driver's software state.
If more explicit power handling is required (i.e. to power off the peripheral from the Miniport), the Miniport could register itself as a Stream Interface driver and receive notifications on Power-Down and Power-Up system events. This option should only be required if the platform does not perform the necessary power handling of the peripheral in the OAL. Also, Miniport drivers which register as Stream Interface drivers should not call any NDIS functions in the power handler except raw I/O functions. For more information on restrictions in power handling for Stream Interface drivers, please refer to the Windows CE Driver Development Kit.
- IrDA NICs. IrDA Miniports are required to export an additional mechanism for power management. This allows the IrDA miniport to power down when there are no Infrared sockets open. (Infrared sockets are exposed through extensions to the WinSock application interface). The following describes the expected operation of an IrDA miniport:
- The miniport is initialized without hardware resources.
- When the first infrared socket is opened, the miniport receives the OID_IRDA_REACQUIRE_HW_RESOURCES message through its set information handler. The miniport then acquires all hardware and software resources for the miniport to operate.
- When the last infrared socket is closed, the miniport receives the OID_IRDA_RELEASE_HW_RESOURCES message through its query information handler. The miniport then releases all hardware resources.
If the Miniport is not concerned with such power management, the Miniport can initialize with all resources and treat the set/query OID requests as null operations. This decision is made based on the requirements of the WCE target platform.
Unlike Windows NT, the Windows CE implementation of NDIS does not inherently support DMA operations. There are two methods depending on whether the NIC is a slave-DMA NIC or a busmaster-DMA NIC.
- Slave-DMA NIC. In Windows NT, a miniport uses NdisMRegisterDmaChannel, NdisMDeregisterDmaChannel, NdisMSetupDmaTransfer, NdisMCompleteDmaTransfer, and NdisMReadDmaCounter for slave-DMA transfers. But, the Windows CE implementation of NDIS does not implement these functions. Instead, the required functionality may be implemented directly in the miniport driver code or in a separate DLL for a particular platform, such that multiple drivers may share the DLL code.
The NSC IrDA miniport sample code in Windows CE 2.1 implements slave-DMA for an 8237 DMA Controller for FIR data transfer in the miniport. In the sample code, the miniport has a physical memory block (reserved from device's memory map) which is mapped to virtual address pointers using VirtualAlloc/VirtualCopy. The miniport then has a shared memory block for send and receive packet buffers: virtual address pointers for use in the miniport and physical addresses for setting up the DMA controller.
- Busmaster-DMA NIC. On Windows NT, a miniport will use NdisQueryMapRegisters, NdisMAllocateMapRegisters, NdisMAllocateSharedMemory, NdisMFreeSharedMemory, NdisMStartBufferPhysicalMapping, NdisMCompleteBufferPhysicalMapping to facilitate DMA transfers for busmaster-DMA NICs. But, the Windows CE implementation of NDIS does not implement these functions, hence the miniport will need to implement the equivalent functionality as described below. Note that these functions were mistakenly exported by the NDIS interface in Windows CE version 2.1 and earlier, but the functionality was not implemented.
In general for a Windows NT miniport, data received by a busmaster-DMA NIC is transferred directly into device-accessible buffers within a shared memory block allocated by the miniport. The miniport calls NdisMInidcateReceivePacket to indicate the packet to the protocol. A Windows CE miniport would likely use the same implementation for the receive path. Shared memory blocks may be setup as described above in the slave-DMA NIC section.
To transfer packet data for a send request, a Windows NT miniport basically does the following:
- Maps the virtual range containing the data with NdisMStartBufferPhysicalMapping to get mapped device-accessible range addresses for use by its NIC.
- Downloads the returned physical addresses to the NIC.
- Calls NdisFlushBuffer and NdisMUpdateSharedMemory if the driver allocated cached memory.
- Programs the NIC for the transfer operation.
- Calls NdisMCompleteBufferPhysicalMapping, usually from the MiniportHandleInterrupt function, when the NIC has completed the transfer, which the NIC indicates by a transmit interrupt or, possibly, by a state change discovered by the NIC driver's polling MiniportTimer function.
For small send requests (< 256 bytes), the miniport can possibly achieve higher performance by copying the bytes into a shared memory buffer, since the Miniport then does not need to map the protocol's send buffer.
On Windows CE, a Miniport can use the functions LockPages/UnlockPages in place of the NDIS functions, NdisMStartBufferPhysicalMapping and NdisMCompleteBufferPhysicalMapping, for mapping virtual addresses to physical address ranges.
Windows CE does not support the Common Network INF file format for installing devices drivers that is used in Windows NT. Instead, Windows CE uses the Registry file for dynamically installing and binding all Driver Developments. Hence, you must ensure that appropriate registry key settings are created for your Miniport driver in the Windows CE registry.
There are several Registry key settings that are common to both built-in and PC Card type of Miniports. However, there are some distinct settings that apply to each type and you must pay careful attention to them. This section describes these settings in detail. Note that the TCP/IP protocol stack supports Miniports for both built-in and PC Card Ethernet hardware. The TCP/IP protocol may bind to multiple Miniport driver instances - allowing it to use multiple NICs. The IrDA protocol stack may only bind to one built-in Miniport driver instance.
Common Registry Keys for Miniport Drivers
When a Miniport driver is installed on a Windows CE-based platform, the setup program should create several registry keys in order to correctly expose the Miniport driver to the Windows CE system. These common registry settings provide driver-specific information to the OS - such as, Miniport type (Group=NDIS), the driver name, driver instance(s), and other information like bus type and number. Windows CE will load all the NDIS drivers listed within the HKEY_LOCAL_MACHINE\Comm\ key, where each key is any arbitrary string value identifying the Miniport driver. Each Miniport\ key contains the following subkeys.
|DisplayName||A user-friendly name for the driver|
|Group||The literal value NDIS|
|ImagePath||The name of the DLL containing the Miniport driver|
|Linkage\Route||A set of Miniport instance keys|
|Miniport Instance||BusNumber and BusType keys|
The value of the Linkage\Route key lists subkeys for each Miniport instance. These subkeys in turn contain keys called BusNumber and BusType, which correspond to the bus used by that particular Miniport driver instance. BusNumber values start at 0. Valid BusType values are declared in the header file CEDDK.H. The following example shows a set of registry keys for a Miniport driver.
[HKEY_LOCAL_MACHINE\Comm\NE2000] DisplayName="NE2000 Compatible Ethernet Driver" Group ="NDIS" ImagePath="NE2000.DLL" [Linkage] Route="NE20001, NE20002" [HKEY_LOCAL_MACHINE\Comm\NE20001] DisplayName="NE2000 Compatible Ethernet Driver" Group ="NDIS" ImagePath="NE2000.DLL" [Parms] BusNumber=0 BusType=8 [HKEY_LOCAL_MACHINE\Comm\NE20002] DisplayName="NE2000 Compatible Ethernet Driver" Group ="NDIS" ImagePath="NE2000.DLL" [Parms] BusNumber=0 BusType=8
Registry Keys for Built-In Miniports
At Windows CE system boot time, NDIS interface will load all the drivers under HKEY_LOCAL_MACHINE\Comm that has "Group" value set to "NDIS". Then, NDIS calls the DriverEntry entrypoint function in each Miniport driver. When the driver registers as a Miniport via the NdisMRegisterMiniport function, then the initialize handler of the Miniport is called.
Built-in Miniports are bound to a protocol by indicating the linkage associated with the protocol in the registry. For Ethernet Miniports:
[HKEY_LOCAL_MACHINE\Comm\Tcpip\Linkage] Bind = PPP, <miniport instance>
Note that the TCP/IP linkage registry key may indicate for IP to bind to a PPP interface as well. Below is an example that shows the NE20001 Miniport instance and the PPP interface being bound to the TCP/IP protocol.
[HKEY_LOCAL_MACHINE\Comm\Tcpip\Linkage] Bind = PPP, NE20001
For IrDA Miniports, the following is the registry key that is used.
[HKEY_LOCAL_MACHINE\Comm\IrDA\Linkage] Bind = <miniport instance>
Below is an example that shows the Serial IR Miniport driver being bound to the IrDA protocol via the Linkage registry key.
[HKEY_LOCAL_MACHINE\Comm\IrDA\Linkage] Bind = IRSIR1
Registry Keys for PC Card Miniports (Plug and Play)
In addition, PC Card Miniport drivers require an HKEY_LOCAL_MACHINE\Drivers\PCMCIA\Plug-and-Play ID\ registry key. This key typically is named after the Plug and Play ID of the PC Card, but this is not a requirement. The key contains the following subkeys.
|DLL||The literal value NDIS.dll|
|Prefix||The literal value NDS|
|Miniport||The name of the Miniport driver for the PC Card, which corresponds to the name of the registry key within HKEY_LOCAL_MACHINE\Comm\ for the Miniport driver.|
For example, a PC Card network adapter could have the following additional keys.
[HKEY_LOCAL_MACHINE\Drivers\PCMCIA\NICs-R-Us Inc.-Super2000-E6FE] DLL="NDIS.DLL" Prefix= "NDS" Miniport="NE2000"
The NDIS Interface sets values for the BusNumber and BusType keys for PC Card network adapters. The BusNumber key will contain the socket and function pair for the network adapter. The BusType key will contain the value for the PC Card bus. Finally, if the card information structure (CIS) of the PC Card contains a network address value, NDIS.dll will create a \HKEY_LOCAL_MACHINE\Comm\<Miniport Name>\<Miniport Instance>\Network Address key to store the network address.
When a recognized PC Card NIC is inserted, PC Card Services calls NDIS to load the Miniport driver. NDIS calls the DriverEntry routine. As with the built-in Miniport drivers, the DriverEntry routine registers the driver as a Miniport and the driver's initialize handler is called. Once the Miniport is initialized, NDIS calls the bind adapter handler for TCP/IP, which subsequently calls NdisOpenAdapter to setup the binding between the Miniport and the protocol. The binding is only established if the supported media of the protocol and the Miniport match.
And finally, PC Card Miniport drivers typically implement an Install_Driver function for installing the appropriate registry settings that will allow for dynamic recognition and installation of the NIC/Miniport. For example, when a NIC PC Card is inserted into a Windows CE system, it tries to recognize the appropriate driver for the card by matching its PnP ID with an appropriate key in the registry. If the system fails to find a PnP match, then it will prompt the user for a user-supplied driver name. If this user-supplied driver DLL exports an Install_Driver function, the system calls this function. The primary purpose of this function is to populate the Windows CE registry with appropriate entries for this Miniport driver, as described above, such that future insertions of the NIC card will lead to dynamic loading of the correct NDIS Miniport driver.
NDIS Netcard Driver Tests
The Windows NT NDIS Netcard Driver Tester program is used to test network drivers and network interface cards in all Microsoft operating systems. For simplicity, we will refer to the NDIS Netcard Driver Tester program as NDISTest in this white paper. The NDISTest program performs two important tasks: it verifies your network interface card (netcard) and driver's operations, and at the same time ensures that your product conforms to the Network Driver Interface Specification (NDIS) version 4.0. Note that NDIS 3.0 drivers are no longer being certified for Windows NT or Windows 9x or Windows CE.
NDISTest verifies the functionality of each NDIS request supported by the netcard driver. The tester works by stressing the packet send and receive functions. The tester emulates a transport layer protocol driver and communicates with the netcard driver through the NDIS wrapper. To test a variety of network configurations, multiple instances of the tester are be bound to each driver. With this you can simulate up to eight network stacks installed onto the same machine.
NDISTest on Windows CE
NDISTest on Windows CE works in a manner similar to NDISTest on Windows NT and Windows 9x. It is recommended that the reader be familiar with Windows NT version of the NDISTest software as documented in the Microsoft Windows NT Version 4.0 Driver Development Kit. Primary differences between the Windows CE and Windows NT versions are that Windows CE supports only a subset of the tests that are available on Windows NT, and that the Windows CE version lacks a GUI to configure and start the tests. The subset of the tests that Windows CE supports is limited to the functional testing of the Ethernet devices.
NDISTest and all other Windows CE driver test routines are part of the Windows CE Driver Development Test Kit (DDTK) Version 2.1 toolkit. Please refer to the DDTK 2. 1 product for complete information on how to setup, run, and test with NDISTest on a Windows CE platform. The DDTK toolkit was not included in the Windows CE Embedded Toolkit version 2.1, but it is currently available as part of the Windows CE Driver Repository. However, later releases of the Window CE Embedded Toolkit (starting from version 2.11) will include the DDTK toolkit.
To run NDISTest requires a Windows CE device with a NIC or netcard. This allows 1-machine functional testing to be performed. To perform 2-machine functional testing, you will need a Windows NT system with a netcard that is connected to a Windows CE machine with its own netcard.
It is recommended that debug output from the Windows CE device be monitored. It is also recommended that a debugger be connected to the CE system such that exceptions and breakpoints that are encountered can be effectively detected and analyzed.
And finally, note that NDISTest for Windows CE has been successfully tested on x86, SH3, and Sh1 processors. It should work on other processors, but this functionality has not been tested as part of the shipping Windows CE operating system.
Windows CE provides a wealth of tools and information on how to debug Driver Developments and system-level OAL components in the operating system. These debug tools and techniques can be applied to debug NDIS Miniport drivers as well. This white paper provides a brief description of the debug tools, but you should consult the Embedded Toolkit documentation for further information on each of these tools. There are 3 essential debug services that allow for debugging Driver Development modules under Windows CE.
- Debug Zones: Debug Zones provide limited debugging capabilities by enabling macros that output debug messages from a Driver Development. Debug message output is a convenient method to trace program execution of a Miniport driver without halting the Windows CE operating system and is especially useful for error conditions. For example, the Miniport driver module can be broken into several debug zones and, by turning these zones on and off, you can control the debug message output from the driver. Although a simple method of debugging, it is quite powerful and the most non-intrusive method of debugging under Windows CE.
- Windows CE Debug Shell (CESH) Tool: The CESH tool is a text-based remote debug shell that can be used in conjunction with Debug Messages to provide limited debugging capabilities or with the Kernel level debugger to debug a Driver Development.
- Microsoft WinDbg Tool: Windbg program is a full-featured debugger program that allows you to perform kernel-level debugging and driver debugging in kernel mode. Windbg is typically used in association with the Kernel level debugger component, namely KDSTUB. This is the most common and powerful method of debugging Driver Developments under Windows CE. It allows the driver to debug by halting the Windows CE system, setting breakpoints and stepping into code, watching callstacks, and so on. In essence, this is the most convenient method to debug exceptions in the Driver Development code and system crashes.
In addition, note that prior to Windows CE version 2.1, all the above debug services were tied to a specific transport (for example, debug messages and the Windbg debugger always went to the serial port, CESH always over the parallel port, and so on). With Windows CE version 2.1, this has been made more configurable so as to support systems with limited capability (such as those without parallel ports). In particular, Ethernet debug support has been added to the operating system such that any of the debug transports can use the high-speed Ethernet transport. Please note that debug Ethernet support is completely different from NDIS Ethernet support. To enable debug Ethernet support on Windows CE, you require a dedicated Ethernet NIC, separate from the one accessed through NDIS Ethernet services.
Once you have developed and tested a NDIS Miniport driver, the next obvious question is - "how to distribute your NDIS Miniport driver to the majority of Windows CE customers?" In order to facilitate such embedded and driver developers, the Windows CE group has created the Windows CE Driver Repository program. The Driver Repository serves the following primary purposes at this time:
- Provides a central location for all Windows CE OEM/IHVs to collect/advertise/publicize their Windows CE driver software for use by Windows CE embedded customers.
- Serves as a valuable resource for all embedded customers that are looking for Windows CE driver software to support their specific hardware.
- Extends the range of devices and hardware that will be available and supported on Windows CE platforms.
Important Any driver software or product that is published or available on the Windows CE Driver Repository Web site is solely the property of the 3rd party OEM or IHV vendor. They are not the property of Microsoft, nor are they supported or endorsed by Microsoft in any way.
In the future, the Windows CE Driver Repository will move towards the concept of a "Windows CE Driver Library", also known as the CEDL. Although the Driver Library is still in the planning stages and the implementation details are not finalized, it will most probably consist of Windows CE Driver software that has been verified and/or tested for the Windows CE operating system by the Microsoft WHQL program. In essence, the main difference between the current Driver Repository and the future Driver Library programs would be in the WHQL certification process and possibly an associated logo. Since we are still in the early stages of planning the Driver Library program, interested customers should periodically check Microsoft Hardware Certification.