WinDriver FAQs

A device driver is a software module that controls hardware. In today's operating systems, this software module usually resides in the kernel mode (ring 0). However, WinDriver enables you to write this code in the user mode, utilizing our lower-level kernel driver(s), and thus frees you from the need for any driver development knowledge. For a better understanding of the basic WinDriver architecture, refer to the WinDriver Architecture page on our site.
WinDriver also includes the Kernel PlugIn feature, which allows you to 'drop' sections of your user-mode code into the kernel mode for better performance and greater flexibility (for PCI/CardBus/PCMCIA/PCI Express/ISA).
Whether the code you develop resides in the user mode or the kernel mode, it is still the code driving the hardware, and therefore it is a driver (but you can call it anything you like ...).

Using WinDriver, you gain the following benefits:

• Cost — Save 90% of the development time.


• Reliability — WinDriver has been market tested thoroughly in thousands of applications (see the Testimonials page for more on this). It has been debugged on almost every platform in the market. Therefore it not only speeds your development time, but cuts your debugging time as well.


• Time to market — WinDriver is ready for you today. Using WinDriver will drastically shorten your development cycle.


• Flexibility — WinDriver supports multiple operating systems, such as Windows 7, Vista, Server 2008, Server 2003, and XP, Windows CE (including Windows Mobile), and Linux (depending on the version you are using) — so even if you only need your driver on one platform today, using WinDriver gives you the flexibility of running under any platform tomorrow. (Please refer to Technical Document #4 for a list of the supported operating systems for each type of hardware — PCI/ISA/USB).


• Stability — WinDriver keeps you away from the OS kernel. While our pre-written kernel module is doing all the transactions with your hardware, you write your code in the protected application mode. This way you get a kernel mode driver (written by our experienced developers), which was tested on practically any OS/platform/BIOS combination available and was found rock stable.

Not at all. With WinDriver, you are coding your device driver in the user mode. WinDriver already provides you with the lower level kernel mode driver, which implements the WinDriver API (see the WinDriver Architecture page on our site). You can, therefore, use your favorite development environment to program and debug your driver, in the user mode, thereby drastically decreasing your device driver development time.

Recommended development steps:

1. Start DriverWizard — WinDriver/wizard/wdwizard (or /Applications/wdwizard.app on Mac OS X — in WinDriver versions that support this OS). On Windows, you can also run the DriverWizard using the shortcut icon on your desktop, or from Windows' Start menu: Start --> Programs --> WinDriver --> DriverWizard.


2. Use the graphical DriverWizard to easily diagnose your hardware, without writing a single line of code. For PCI/ISA — read/write the hardware resources (memory/IO/registers) and listen to interrupts.
   For USB — transfer data on the pipes, reset the device, etc.


3. Select the "Generate Code" option from the toolbar, or press the Next button. Select your target compiler/development environment, and let the DriverWizard create a skeleton of a device driver application for your device. The generated code will include convenience structures and functions, which utilize WinDriver's basic API to access the resources detected and defined (by you) for your hardware.
   
   You can use the DriverWizard to generate code in C, C#, or Visual Basic .NET (VB.NET) (USB only); earlier versions (until v11.2.0) also supported code generation in Delphi (Pascal) or Visual Basic (VB 6.0). The DriverWizard will also create makefiles and the relevant build environment for leading 32-bit and 64-bit compilers — such as MS Visual Studio, GCC, or Windows GCC (MinGW/Cygwin).
   
   You can also use one of the WinDriver samples as the basis for your development. Specific samples for enhanced-support hardware can be found under the relevant directory for that hardware, such as PLX, Altera, Cypress, etc. — see the for more information regarding WinDriver's enhanced support for specific PCI and USB chip sets.
   General samples, in C, can be found in the WinDriver/samples directory.
   .NET samples are found in the WinDriver/csharp.net (C#) and WinDriver/vb.net (VB.NET) directories (beginning with v7.0.0 of WinDriver).


4. Use the manual and help files to modify the generated diagnostics code and add the specific functionality that you need (if any), in accordance with your hardware's specification.
   The WinDriver user's manuals and help files are found in the WinDriver/docs directory and can also be accessed via Windows' Start menu (for Windows users). All documents are also available online from the page.


5. Compile and build your code (from the user mode!) using any 32-bit or 64-bit compiler.

DONE!

Yes. Jungo provides full-featured evaluation versions of the WinDriver tool-kit. The trial versions can be downloaded from the Downloads page on our site. The limitations of each evaluation version (as compared with the registered version) are outlined in the WinDriver User's Manual and in Technical Document #9.

Yes. All versions of WinDriver are backwards compatible, except for rare occasions documented in the WinDriver Release Notes. In most cases, code compiled with an earlier WinDriver version will work, without recompilation, after replacing the driver file with that from a newer version; on Windows you may also need to replace the device's INF file with one from the newer version.
One exception is when upgrading from version 5.2.2 and below to version 6.0.0 and above: In version 6.0.0 we renamed the WinDriver kernel module from windrvr to windrvr6, therefore upgrading to a version that uses the new driver requires rebuilding the code with the header files from the new version (see Technical Document #116); the old API will still be supported, for backwards compatibility, after rebuilding the code.
It is recommended, however, to always use the newest API, to fully utilize the improvements introduced in newer versions.

NOTE: The Kernel PlugIn is not backwards compatible. Therefore, when upgrading to a newer version of WinDriver, you must also rebuild your Kernel PlugIn driver (if you have created such a driver) using the new version.

First, review the support resources available on the WinDriver Support page. If you cannot find an answer to your problem, use our Secured Support Center (or the Non-Secured Support Center) to report a problem or get any type of product support.
To ensure a quick and effective response, be sure to specify all relevant information, as outlined in the support center and below.
You can also contact us by telephone. If you call outside our office hours, or if all support personnel are occupied, leave your full contact details (name, company name, email and phone numbers) and we will be sure to contact you shortly.

When reporting a problem, please include a clear description of all the steps you performed, and specify which step failed and what was the exact nature of the failure or erroneous behavior that you encountered (including complete error messages).

Please check specifically that you have included the following information:

1. In general, please indicate
   
   • Your operating system. For example: Windows Vista 64-bit; Windows XP SP3; Windows Embedded Compact 7, Windows CE v7.0; RedHat Linux 7.2, Linux kernel version 2.6.32-5-686.
   • Your WinDriver version. For example: WinDriver version 11.2.0.
   • The entire output of the Debug Monitor utility: Run the Debug Monitor, set the debug level to 'Trace', reproduce your problem and attach the output from the Debug Monitor window (including the version information at the top).


2. For licensing problems: In addition to the Debug Monitor log, please be sure to specify your full license registration string, which you received when purchasing the software, and your development computer's registration code. You can view the license registration string and the PC registration code from the DriverWizard's Licensing Information window (File --> Registration Options).


3. For PCI related problems: In addition to the Debug Monitor log, please also attach the entire output of the pci_dump utility (found in the WinDriver/util directory), and be be sure to specify your card's vendor ID and device ID as well.


4. For installation related problems, in addition to the Debug Monitor output, be sure to specify the exact installation steps that you performed (which files were copied to which directories; usage of the wdreg installation utility; installation of INF files; etc.) and the result of each step, and attach a copy of the exact error message that you received (if any).
   On Plug-and-Play Windows platforms (Windows 7/Vista/Server 2008/Server 2003/XP/2k/Me/98), please also attach a copy of the device INF file that was used in the installation (if any), and a copy of the %WINDIR%\setupapi.log file from the PC on which the problem occurred.

Please contact sales@jungo.com to request an extension of the evaluation period. Please also refer to the WinDriver User's Manual and to Technical Document #9 for a description of the evaluation limits of the different WinDriver kits.

Jungo provides tool kits for writing device drivers. We do not provide ready-made drivers for commercial hardware.

To completely remove WinDriver from your computer, follow the instructions found at the Uninstall Page on our site. NOTE: The online uninstallation instructions are for the latest WinDriver version. If you are using an older version, follow the uninstallation instructions in the WinDriver User's Manual for your specific version.

Simply order the product from our online store. Alternatively, download a text order form, and email it to sales@jungo.com, or Fax it to "Jungo — Connectivity Software Department" (see the contact details on our site).

Your registered license will include the registered WinDriver version, official documentation and 2 months of free product upgrades and technical day support.

To get technical support or be eligible for version upgrades after the expiration of the complimentary two months support and maintenance period, you must subscribe to the WinDriver annual Upgrade & Support plan. You can subscribe to this plan from the online store.
For more information regarding the support & maintenance plan, refer to the Support Purchase page. The prices of the support plans are derived from the prices of the original licenses. As you will be able to see, it is much cheaper to subscribe to the upgrade and support plan during the period of a current valid upgrade & support subscription (including the 2 months complimentary upgrade & support period). Once you subscribe to this plan, use Jungo's Secured Support Center (or the Non-Secured Support Center) to contact our support team at any time. Please also refer to the following FAQ to find out how to report a problem effectively: http://www.jungo.com/st/support/faq.html#lfc.

After purchasing the license from Jungo, you own your driver. The license is issued for the development stage. The executable/DLL that you create is yours to distribute freely, in as many copies as you wish. No royalties are to be paid to Jungo. The only exception to this is if you have created a driver development kit with WinDriver. For this reason you cannot distribute the WinDriver header files or your license registration string, thereby enabling others to develop a driver with WinDriver. For more information, take a look at the Distributing Your Driver — Legal Issues Appendix in the WinDriver User's Manual or contact sales@jungo.com.

When using a registered version of WinDriver, you must register your specific license registration string from the code.

The generated DriverWizard code for the registered tool-kit will already include the relevant code for registering your license (provided you have activated your license from the wizard before generating the code). However, if you used the DriverWizard to generate the code during the evaluation period, or if you are using one of the WinDriver samples, you will need to add the registration code yourself.

Note that after the initial registration of the license from the DriverWizard, your license string will automatically be activated with every session of the wizard. This is the reason that you have found that your code seems to work if you first run DriverWizard (since the license was already registered from the wizard, even though it was not explicitly registered from the code).

Please refer to the description of WDU_Init() (USB) / WDC_DriverOpen() (PCI/ISA) in the WinDriver User's Manuals to learn how to correctly register your license registration string from the code.
If your codes uses the low-level WD_xxx APIs instead of the WDU or WDC APIs, use the function WD_License() to register your license string. WD_License() is described in the WinDriver PCI Low-Level API Reference (WinDriver/docs/wdpci_low_level_api_ref.pdf) in v8.0.0 and above of WinDriver. In earlier versions the function is described in the WinDriver User's Manual, which is found under the WinDriver/docs/ directory for the specific version. (If you are using version 5.0.5b or earlier of WinDriver, you can refer to the WinDriver/redist/register/register.txt file for relevant registration instructions).

Beginning with version 5.2.0 of WinDriver, the generated DriverWizard evaluation code already includes the required license registration code, but using a demo license string. When moving to a registered version you simply need to replace the demo license string that is used in the call to WDU_Init() / WDC_DriverOpen() / WD_License() in the evaluation code with your specific license registration string.

NOTE: Make sure that your code calls the license registration function before any other WinDriver API call (apart from WD_Open or WD_Version(), when using the low-level WD_xxx APIs).

When installing WinDriver, the only thing that will be locked to one machine is the development environment — i.e., the DriverWizard (unless you are using a floating WinDriver license, which enables you to use the DriverWizard on any PC). Once you have written and built your code, you may install and run it on any machine you want. The device driver you create using WinDriver is yours to distribute in as many copies as you wish, royalties free, provided you do not distribute your own driver development kit (see the following FAQ: http://www.jungo.com/st/support/faq.html#MIP).
To find out how to distribute the driver you developed with WinDriver, please review the driver distribution chapter in your WinDriver User's Manual, and the distribution technical documents for your WinDriver version in the Licensing And Distribution section of the WinDriver Technical Documents. Please note that before distributing your driver you must register your license registration string from the code, as explained in the manual and in the following FAQs: http://www.jungo.com/st/support/faq.html#reg1 and http://www.jungo.com/st/support/faq.html#lfc19.

The Debug Monitor (a.k.a. Monitor Debug Messages, in older WinDriver versions) is an application program that logs detailed debugging information from the WinDriver kernel driver(s). This application is available in two versions: wddebug_gui — a fully graphical version; and wddebug — a console-mode version, which also supports GUI execution on Windows CE platforms (beginning with v10.0.1 of WinDriver).
Both versions of the Debug Monitor can be found at WinDriver/util; (on Mac OS X, in WinDriver versions that support it, the GUI version can be found in the OS's /Applications folder).
For detailed information on this utility and how to use it, refer to the WinDriver User's Manual, and to the following Technical Documents:
#12 (wddebug_gui for Windows, Mac OS X, Linux, and Solaris), #13 (wddebug for Windows, Windows CE (including Windows Mobile), Mac OS X, Linux, and Solaris), and #14 (wddebug for VxWorks — last supported in WinDriver v5.2.2).
For information regarding redirecting debug information from the Debug Monitor to a kernel debugger, refer to Technical Document #44.

NOTE: The Debug Monitor can also be run on target platforms on which only on the WinDriver driver(s), and not the entire WinDriver tool-kit, have been installed. This can be useful, for example, for debugging problems on your customers' platforms, as explained in the following FAQ:
http://www.jungo.com/st/support/faq.html#lfc6009.

Yes. You can select to send the debug information from the Debug Monitor to a kernel debugger, as explained in Technical Document #44.
On Windows, in order to save the debug information in case of a hang/crash, you will need to install the kernel debugger on another PC and establish a debug session between this PC and your development PC. For more information on what to do in case of a crash on Windows, refer to Technical Document #121. On Linux you will find the debug log, after reboot, in /var/log/messages.

WinDriver provides an API for accurate sleep times (in 1 microseconds resolution) — WD_Sleep().

By default, WD_Sleep() performs a busy sleep.

If you need to perform a non-busy sleep:

• If a resolution of ~17,000 microseconds is sufficient for you, then you can either set up the SLEEP_NON_BUSY flag in the dwOptions field of the WD_SLEEP structure, which is passed to WD_Sleep(), in order to perform a non-busy sleep; Or use the standard OS sleep functions (e.g., Sleep(), WaitForSingleObject(), etc.). Using WD_Sleep() will maintain your code's portability, as opposed to the standard OS sleep functions.


• If you need a higher resolution, you can write a Kernel PlugIn application, using the Virtual Timer Device (VTD) API in Win95. The problem is that the code that will execute on the timer is kernel mode code. You will have to write code to transfer the data from user mode to kernel mode, and then transfer the results back from kernel mode to user mode.

YES! The code of the device driver you write runs in normal Win32 user mode. Therefore, you can compile and debug your code using MS Visual Studio / Visual C++.
Please refer to Technical Document #19 for more information regarding debugging your driver code with WinDriver.

If you need to define more than WD_CARD_ITEMS items for your card (currently 20 items, according to the definition of WD_CARD_ITEMS in windrvr.h), do not modify the value of WD_CARD_ITEMS in the code, but instead, simply call WD_CardRegister() several times from your code, with different items each time. (It is not mandatory to lock all the resources on a specific card with a single WD_CardRegister() call.) Alternatively, consider grouping several memory/IO address ranges into a single BAR definition, so that the overall resources item count does not exceed the default 20 items limit.

Please do not change anything in windrvr.h. The affect will certainly not be what you expect and it could be potentially disastrous.

The sample programs were written with the evaluation version in mind (so that they can be distributed and used without a license during the evaluation period). You can modify their source code in order to register your license registration string from the code — as explained in the following FAQ: http://www.jungo.com/st/support/faq.html#reg1.

You can replace the calls to WD_Transfer() with direct memory access, by utilizing the virtual user mode mapping of the base physical address for the relevant memory range, which is returned by WD_CardRegister() in:
cardReg.Card.Item[i].I.Mem.dwUserDirectAddress
(where 'i' is the index number of the memory base address in the WD_ITEMS 'Item' array).
This is documented in the WinDriver User's Manual (see the description of WD_CardRegister() in the "Function Reference" chapter and the "Improving Performance" chapter) and in Technical Documents #74 and #17. Technical document #17 also includes other suggestions on how you might improve your driver's performance with WinDriver.

WinDriver's Debug Monitor utility can run on any machine (unlike the WinDriver DriverWizard utility, which is locked down to the development machine). Therefore, you can simply copy the wddebug_gui or wddebug program file from the development machine (from WinDriver/util or from /Applications on Mac OS X — in WinDriver versions that support this OS), to a target machine on which the WinDriver driver(s) have been installed, and run the Debug Monitor on the target. For detailed information regarding the Debug Monitor utility, refer to the WinDriver User's Manual and to the Debug Monitor FAQ.

The Kernel PlugIn is an integral part of the WinDriver PCI/ISA tool-kit.
No additional license or payment is required in order to use it.

If you are using Kernel PlugIn to develop a Windows SYS driver, you need to install Microsoft's Windows Driver Kit (WDK), or the earlier Driver Development Kit (DDK) — depending on your target OS and WinDriver version — in order to successfully build your Kernel PlugIn driver.
For information regarding acquiring the WDK, refer to: http://www.microsoft.com/whdc/devtools/WDK/WDKpkg.mspx.
[Note that when using the WDK/DDK to build your Kernel PlugIn driver, you will also need to set the BASEDIR or DDKROOT environment variable to the location of your DDK library, as explained in the WinDriver User's Manual.]

Development of VxD Kernel PlugIn drivers, which was supported for Windows 98/Me in earlier versions of WinDriver (v6.0x-), does not require you to install Microsoft's WDK/DDK in order to successfully build the driver, unless you choose to add your own DDK function calls to your Kernel PlugIn application. (Note that using OS-specific DDK functions can damage the driver's portability).

Using WinDriver's Kernel PlugIn feature, you can expect to handle more than 100,000 interrupts per second, without missing any of them.
For sample Kernel PlugIn interrupt handling code, use the DriverWizard to generate code for your device (for PCI and PCMCIA devices, define the data for clearing the interrupt in the wizard before generating the code), or take a look at the WinDriver Kernel PlugIn sample code — KP_PCI (WinDriver/samples/pci_diag/kp_pci — v7.0.0+) or KPTEST (WinDriver/kerplug/kptest/kermode — v6.2.3-a).

In the user mode you can handle around 5,000-10,000 interrupts per second, but since Windows is not a Real Time OS, you might miss some of the interrupts once in a while (although WinDriver tells you when you have missed an interrupt and how many interrupts were missed).

For an explanation regarding interrupt latency with WinDriver, refer to Technical Document #48.

Yes.

WinDriver implements malloc() and free() for kernel mode memory allocation (see Technical Document #34). Since the allocated memory is locked, you can also use this memory in your Kernel PlugIn interrupt routines.
You can also share a memory buffer between the user mode and Kernel PlugIn applications — as explained in Technical Document #41.

Yes — You can erase the user mode interrupt handler routine.
You can also implement some of the interrupt handling in the Kernel PlugIn and some of it in the user mode. The return value of KP_IntAtDpc() (which is called when the high-priority KP_IntIrql() routine returns TRUE) determines the number of times that the user mode interrupt handler routine will be executed (if at all).

Kernel PlugIn enables you to create an add-on *.sys/.kext/.o/.ko kernel driver — depending on your OS — to extend the features of WinDriver for your needs. The Kernel PlugIn driver your create is not standalone — it can only work together with a user-mode driver that activates it.

Note that when using WinDriver's Kernel PlugIn feature, you must also install the WinDriver kernel module — windrvr6.sys/.dll/.o/.ko or WinDriver.kext, depending on the OS and the WinDriver version.

You can use WinDriver's WD_DebugAdd() API (available from v5.0.3 and above) to print debug messages from your Kernel PlugIn or user mode code to the Debug Monitor utility, and then view the messages in the Debug Monitor log. WD_DebugAdd() can be called from within any user-mode or Kernel PlugIn function, including KP_IntAtIrql().

You can also select to send the debug information from WinDriver's Debug Monitor to a kernel debugger, as explained in Technical Document #44.

In addition, you can add calls in your Kernel PlugIn code to OS kernel functions that print directly to the kernel debugger — such as KdPrint() on Windows , or printk() on Linux.

This might happen if you are enabling the interrupt from your Kernel PlugIn interrupt routines, and simultaneously disabling it from the user mode (using WD_IntDisable() or InterruptEnable() / WDC_IntEnable() — which call WD_IntDisable()). Since the interrupt is active (having been enabled from the Kernel PlugIn), the interrupt cannot be disabled and the PC hangs waiting for WD_IntDisable() to return.

A possible solution, is to call WD_IntDisable()/InterruptEnable()/WDC_IntEnable() as an atomic operation, so that it will disable the interrupts successfully before the Kernel PlugIn interrupt routine enables the interrupt.

Please refer to http://www.jungo.com/st/support/faq.html#kplinux under the Linux Issues section for the answer to this question.

No. Only the callbacks used by WinDriver need to be declared as __cdecl.

When writing device drivers, developers must write a separate device driver for the Win 9x and the Win NTx kernels. Microsoft has developed a cross-platform operating system support for input devices, in order to provide a uniform way for code to access such devices across Windows 7, Vista, Server 2008, Server 2003, XP, 2000, 98, and Me platforms. This new support is known as Windows Driver Model or "WDM". WDM is based on the original Windows NT driver model, with modifications to support Plug-and-Play and power management, and is used for most multimedia device types and many other newer device types, such as USB and 1394 devices.
Beginning with version 5.2.0 of WinDriver, WinDriver's kernel module — (windrvr6.sys / windrvr.sys in v5.2.2-) — which implements WinDriver's API, is a full WDM driver.

This message is not actually an error message and is not an indication of any problem in the installation process or with the driver. This message is issued by Microsoft's Windows XP to indicate that the driver was not tested and digitally signed by Microsoft's Windows Hardware Quality Labs (WHQL).

To avoid this message you can contact Microsoft in order to get your driver digitally signed. For more information Click Here.

WinDriver is fully WHQL-compliant. The driver you develop with WinDriver for Windows can be submitted to Microsoft's Windows Hardware Quality Labs (WHQL) testing in order to digitally sign the driver with Microsoft. Several WinDriver customers have already successfully signed their WinDriver-based drivers with Microsoft.
For more information on Microsoft's WHQL testing and how to get a WHQL certification for your hardware and WinDriver-based driver, refer to to the "WHQL Certification" section in the WinDriver User's Manual and to Microsoft's documentation, for example: http://www.microsoft.com/whdc/whql/default.mspx/. For further assistance, contact us via our Secured Support Center (or the Non-Secured Support Center).

Set the PciCfgRwCompat registry key flag in the WinDriver driver INF file (v10.3.1 and higher) to 1 to enable the legacy PCI configuration space read/write method, as explained in Technical Document #2.

Yes — the Debug Monitor utility is also available on Windows CE (including Windows Mobile). For more information, refer to Technical Document #13.

Yes. In Windows CE, device drivers, including NDIS drivers, are DLLs. So a NDIS network driver can use the WinDriver CE API to talk to the hardware.

Yes. In Windows CE, device drivers, including NDIS drivers, are DLLs. So a NDIS network driver can use the WinDriver CE API to talk to the hardware.

Make sure to install the WinDriver kernel module — windrvr6.o/.ko (or windrvr.o — in v5.2.2 or below) — before installing your Kernel PlugIn module, since the Kernel PlugIn driver depends on the WinDriver driver module for its operation.
For detailed Kernel PlugIn installation instructions, refer to the WinDriver User's Manual for your WinDriver version and to Technical Document #62.

This is a limitation in Linux kernels — by default you can allocate a maximum of 128KB for kernel buffer allocation. However, it is possible to recompile the kernel to get larger sizes and there is also a path that enables this — as explained in Technical Document #64.

Yes. You can use the WinDriver PCI tool-kit and API to develop a CardBus driver, as explained in Technical Document #94.

Note that on Plug-and-Play (PnP) Windows operating systems, you need to generate and install an INF file for your device in order to successfully handle it with WinDriver (you can use the DriverWizard to generate the INF file, as explained in the WinDriver documentation). The INF file will register your device to work with WinDriver's kernel driver (windrvr6.sys or windrvr.sys — in v5.2.x / wdpnp.sys/wdusb.sys — in previous versions).

This might be a hardware problem, due to BIOS-specific implementations of parallel port modes on various computers. WinDriver cannot control this behavior, since it is programmed into the BIOS. We advise you to follow the brand of computer or BIOS that you have observed works correctly.

The user-mode interrupts handler can service up to 10,000 interrupts per second (although we cannot commit to a specific number, since this is dependent upon many factors). A latency of approximately 25ms should generally not happen, but it can from time to time. Using WinDriver's Kernel PlugIn feature will ensure that this will not happen. However, nothing can protect against some badly written device drivers that sometimes disable interrupts for long periods. Such offending drivers should be identified and upgraded or removed. For more information regarding WinDriver's interrupt latency, refer to Technical Document #48

When a PCI interrupt occurs, WinDriver writes/reads the interrupt status register in order to clear (acknowledge) the level sensitive interrupt. This is performed directly in the kernel, according to the information that was set up in the code, beforehand, when enabling the interrupt. To read and save the value of the interrupt register before the interrupt is cleared, so that you can later reference this value from within your interrupt handler routine, you need to set up a relevant read command in the interrupt transfer commands that are set up in the dwCmd field of the WD_INTERRUPT structure, which is passed to InterruptEnable() (/InterruptThreadEnable() in earlier versions)/WD_IntEnable(), and set the INTERRUPT_CMD_COPY flag in the dwOptions field of the WD_INTERRUPT structure (int.dwOptions |= INTERRUPT_CMD_COPY).
This is documented in the "Interrupt Handling" section of the WinDriver User's Manual and in Technical Documents #104 and #75.

PCI uses level sensitive interrupts, which must be acknowledged and cleared in the kernel immediately when they are received. Therefore, WinDriver requires you to define an interrupt status register, which should be read/written in order to clear the interrupt. This is a precautionary feature, because a level sensitive interrupt that is not acknowledged can hang your PC. Please refer to Technical Document #105 for a detailed explanation on how to listen to PCI interrupts with WinDriver's DriverWizard. Please also refer to Technical Document #75 and to the WinDriver User's Manual for a general explanation regarding the handling of PCI interrupts with WinDriver.

NOTE that as specified in the WinDriver documentation, in order to handle PCI interrupts correctly with WinDriver on Plug-and-Play (PnP) Windows operating systems, you must first install an INF file for the device, which registers it to work with WinDriver's PnP driver (windrvr6.sys in the latest WinDriver versions; in previous versions — windrvr.sys/wdpnp.sys/wdusb.sys, depending on the version).

Yes. Beginning with version 9.1.0 WinDriver supports Message Signaled-Interrupts (MSI) and Enhanced Message-Signaled Interrupts (MSI-X) on Windows Vista and higher and Linux.
Support for additional operating systems will be added in future versions of WinDriver.

NOTE: Support for MSI/MSI-X on Windows is provided only on Windows Vista and higher, because earlier versions of Windows do not support these types of interrupt.

For more information on WinDriver's MSI/MSI-X support, refer to the WinDriver User's Manual.

To lock a large DMA buffer (more than 1MB) for Scatter/Gather (S/G) DMA (i.e., when the KERNEL_BUFFER_ALLOC DMA options flag is not set), using WD_DMALock() function, perform the following steps.

1. Set the DMA_LARGE_BUFFER flag in the dwOptions field of the WD_DMA structure whose address is passed as the pDma parameter of WD_DMALock() ("the WD_DMA structure"). (Note: This flag is required only when performing Scatter/Gather DMA, as opposed to Contiguous Buffer DMA.)


2. Calculate the number of pages you need to lock, in the following manner, and assign it to the dwPages field of the WD_DMA structure:
   
   dwPagesNeeded = transferCount / 4096 + 2;
   
   where transferCount is the number of bytes that you want to lock.


3. NOTE: By default, the WD_DMA structure can hold information of up to 256 pages (= WD_DMA_PAGES, defined in WinDriver/include/windrvr.h). If you wish to lock more than 256 pages, you need to have enough memory to hold the information of all the pages. To allocate memory for the additional pages' information, you can do the following:
   
   WD_DMA *pDma;
pDma = (WD_DMA *)malloc(sizeof(WD_DMA) +
   sizeof(WD_DMA_PAGE)*(dwPagesNeeded - WD_DMA_PAGES));

If the memory allocation still fails (using either WDC_DMASGBufLock(), or WD_DMALock() in the manner outlined above), verify that there are sufficient system resources for the attempted memory allocation (both in the kernel and in the user mode address space to which the memory is mapped).
On Windows, you may need to increase the size of the non-paged pool (from which the memory is allocated), as explained in Technical Document #58.
If you still cannot lock the entire buffer, try locking a smaller buffer.

For more information regarding performing DMA with WinDriver, please see the section regarding "Performing DMA" in the "WinDriver Implementations Issues" chapter of the WinDriver PCI User's Manual, and to the description of the WinDriver DMA APIs in the "Function Reference" chapter of the manual.

"Regular" memory (stack, heap, etc.) is cached by the operating system. When using WD_DMALock(), the data is non-cached, in order to make it DMA-safe. Therefore, the memory access is slower. Note that this is the correct behavior for DMA.

When performing Contiguous Buffer DMA, you can set the DMA_ALLOW_CACHE flag in the dwOptions paramer of WDC_DMAContigBufLock, or directly in the dwOptions field of the WD_DMA structure that is passed to WD_DMALock() (when using the low-level WinDriver API), in order to allocate a cached DMA buffer. When working on Windows x86 and x86_64 platforms, it is recommended to always set this flag.
(Note: The DMA_ALLOW_CACHE flag is available beginning with version 5.2.1 of WinDriver.)

If you have allocated the memory in the user mode and then passed its address to WDC_DMASGBufLock() or to the low-level WD_DMALock() function in order to lock a Scatter/Gather DMA buffer, then calling WD_DMAUnlock() will unlock the memory buffer and it will now function like other "regular" memory in terms of access speed.