• Download demo source project - 160 Kb

Introduction

A lot of articles have been investigating in application layer issues, like skin-based dialogs, MFC, ATL, thread, process, registry etc. It won't be easy to find any driver related articles posted with full source code. The root cause is that most drivers are developed for specific hardware. Without the domain knowledge, you will never want to get in touch with it. I believe a lot of software engineers are afraid when they involve in kernel mode programming for the very first time, and there are not too much resources that can guide them through the whole process from DDK study to program stage. Hence I decided to share some of my experiences in driver programming in Windows. This demo focuses on a quick introduction to WDM Driver's architecture, and will introduce two I/O modes coming with Windows, which are Direct I/O and Buffered I/O, how to communicate with drivers residing in system kernel space, and read/write data to it.

There is no need for you to read the demo program with any hardware related background, the demo drivers are all pseudo drivers. That's drivers installed without a physical device in computer.

The member functions defined in this demo program can be used as templates for later driver development by you.

Background

You might be a well-experienced software engineer and might want to involve in kernel programming.

Create your WDM Driver: a Pseudo Driver tutorial

Before we start, declaration for member routines and structures is required. The most important driver-required data structure is - DEVICE_EXTENSION!

typedef struct tagDEVICE_EXTENSION {
    PDEVICE_OBJECT DeviceObject;       // device object this driver creates
    PDEVICE_OBJECT NextDeviceObject;   // next-layered device object in this
                                       // device stack
    DEVICE_CAPABILITIES pdc;           // device capability
    IO_REMOVE_LOCK RemoveLock;         // removal control locking structure
    LONG handles;                      // # open handles
    PVOID DataBuffer;                  // Internal Buffer for Read/Write I/O
    UNICODE_STRING Device_Description; // Device Description
    SYSTEM_POWER_STATE SysPwrState;    // Current System Power State
    DEVICE_POWER_STATE DevPwrState;    // Current Device Power State
    PIRP PowerIrp;                     // Current Handling Power-Related IRP
} DEVICE_EXTENSION, *PDEVICE_EXTENSION;

Code segment below demonstrates the start of creating a valid WDM Driver.

There are mandatory and optional members in a WDM Driver. A valid WDM Driver should come with the following member routines, the most important task item for DriverEntry is to register all member routines to kernel:

//
NTSTATUS
DriverEntry( 
IN PDRIVER_OBJECT DriverObject, 
IN PUNICODE_STRING RegistryPath 
)
{
RtlInitUnicodeString(
&Global_sz_Drv_RegInfo,
RegistryPath->Buffer);

// Initialize function pointers

DriverObject->DriverUnload = DriverUnload;
DriverObject->DriverExtension->AddDevice = AddDevice;

DriverObject->MajorFunction[IRP_MJ_CREATE] = PsdoDispatchCreate;
DriverObject->MajorFunction[IRP_MJ_CLOSE] = PsdoDispatchClose;
DriverObject->MajorFunction[IRP_MJ_READ] = PsdoDispatchRead;
DriverObject->MajorFunction[IRP_MJ_WRITE] = PsdoDispatchWrite;
DriverObject->MajorFunction[IRP_MJ_DEVICE_CONTROL] = PsdoDispatchDeviceControl;
DriverObject->MajorFunction[IRP_MJ_POWER] = PsdoDispatchPower;
DriverObject->MajorFunction[IRP_MJ_PNP] = PsdoDispatchPnP;

return STATUS_SUCCESS;
}
//

Normal operation workflow within WDM Driver

Code segment below demonstrates the workflow in AddDevice routine: the most important task for AddDevice routine is to create a Device object, and attach it to the existing device stack.

NTSTATUS
AddDevice(
IN PDRIVER_OBJECT DriverObject,
IN PDEVICE_OBJECT PhysicalDeviceObject 
)
{
    ULONG DeviceExtensionSize;
    PDEVICE_EXTENSION p_DVCEXT;
    PDEVICE_OBJECT ptr_PDO;
    NTSTATUS status;

    RtlInitUnicodeString(
        &Global_sz_DeviceName, L"");
    //Get DEVICE_EXTENSION required memory space
    DeviceExtensionSize = sizeof(DEVICE_EXTENSION);
    //Create Device Object
    status = IoCreateDevice(
        DriverObject,
        DeviceExtensionSize,
        &Global_sz_DeviceName,
        FILE_DEVICE_UNKNOWN,
        FILE_DEVICE_SECURE_OPEN, 
        FALSE,
        &ptr_PDO
        );

    if (NT_SUCCESS(status)) {
        ptr_PDO->Flags &= ~DO_DEVICE_INITIALIZING;
        ptr_PDO->Flags |= DO_BUFFERED_IO;  //For Buffered I/O
        //ptr_PDO->Flags |= DO_DIRECT_IO;  //For Direct I/O
        p_DVCEXT = ptr_PDO->DeviceExtension;
        p_DVCEXT->DeviceObject = ptr_PDO;
        RtlInitUnicodeString(

        /*
        //Other initialization tasks go here
        */

        //Store next-layered device object
        //Attach device object to device stack
        p_DVCEXT->NextDeviceObject = 
            IoAttachDeviceToDeviceStack(ptr_PDO, PhysicalDeviceObject);
    }

    return status;
}

Code segment below shows how to support IRP_MJ_CREATE, it is send when client application tries to connect to the underlying Pseudo Driver. Before proceeding, see graph below in advance to realize the connection process.

Usually, you will use CreateFile/fopen Win32 API to connect to the underlying device. It is the right time that Win32 Subsystem submits IRP_MJ_CREATE and asks driver to connect to the target device!

NTSTATUS
PsdoDispatchCreate(
IN PDEVICE_OBJECT DeviceObject,
IN PIRP Irp
)
{
    PIO_STACK_LOCATION p_IO_STK;
    PDEVICE_EXTENSION p_DVCEXT;
    NTSTATUS status;

    p_IO_STK = IoGetCurrentIrpStackLocation(Irp);
    p_DVCEXT = DeviceObject->DeviceExtension;
    status = IoAcquireRemoveLock(&p_DVCEXT->RemoveLock, p_IO_STK->FileObject);
    if (NT_SUCCESS(status)) {
        CompleteRequest(Irp, STATUS_SUCCESS, 0);
        return STATUS_SUCCESS;
    } else {
        IoReleaseRemoveLock(&p_DVCEXT->RemoveLock, p_IO_STK->FileObject);
        CompleteRequest(Irp, status, 0);
        return status;
    }
}

Code segment below shows how to support IRP_MJ_CLOSE, the IRP is sent when client application tries to close connection to the underlying Pseudo Driver. Before proceeding, see graph below in advance to realize the closing process.

Usually, you will use CloseHandle/fclose Win32 API to close connection to the underlying device. It is the right time that Win32 Subsystem submits IRP_MJ_CLOSE and asks driver to close connection to target device!

NTSTATUS
PsdoDispatchClose(
IN PDEVICE_OBJECT DeviceObject,
IN PIRP Irp
)
{
    PIO_STACK_LOCATION p_IO_STK;
    PDEVICE_EXTENSION p_DVCEXT;

    p_IO_STK = IoGetCurrentIrpStackLocation(Irp);
    p_DVCEXT = DeviceObject->DeviceExtension;
    IoReleaseRemoveLock(&p_DVCEXT->RemoveLock, 
    p_IO_STK->FileObject);
    CompleteRequest(Irp, STATUS_SUCCESS, 0);
    return STATUS_SUCCESS;
}

I/O Support : Buffered I/O Mode

There are three I/O modes in Windows kernel, they are Buffer, Direct and Neither modes. Now, we'll talk about Buffered I/O, and this article will not involve Neither mode for data transfer if processing under user-thread occupied memory space, it might be dangerous!! If client application is going to read/write data to and from driver, the memory address of data source will not be directly referenced by the underlying driver. System kernel will allocate another data buffer with equivalent size in kernel. All data transferred must be copied into this area before they are to the target place. Usually, you will call ReadFile/WriteFile or fread/fwrite to make read/write request.

Below code segment demos the workflow in I/O handle for read request. As we can see, the routine that is registered for reading is PsdoDispatchRead in DriverEntry, this member routine will read data out of Driver's internal member - DataBuffer to client application:

NTSTATUS
PsdoDispatchRead(
IN PDEVICE_OBJECT DeviceObject,
IN PIRP Irp
)
{
    PVOID Buf; //Buffer provided by user program
    ULONG BufLen; //Buffer length for user provided buffer
    LONGLONG Offset;//Buffer Offset
    PVOID DataBuf; //Buffer provided by Driver
    ULONG DataLen; //Buffer length for Driver Data Buffer
    ULONG ByteTransferred;
    PIO_STACK_LOCATION p_IO_STK;
    PDEVICE_EXTENSION p_DVCEXT;

    DbgPrint("IRP_MJ_READ : Begin\r\n");
    //Get I/o Stack Location & Device Extension
    p_IO_STK = IoGetCurrentIrpStackLocation(Irp);
    p_DVCEXT = DeviceObject->DeviceExtension;

    //Get User Output Buffer & Length 
    BufLen = p_IO_STK->Parameters.Read.Length;
    Offset = p_IO_STK->Parameters.Read.ByteOffset.QuadPart;
    Buf = (PUCHAR)(Irp->AssociatedIrp.SystemBuffer) + Offset;

    //Get Driver Data Buffer & Length
    DataBuf = p_DVCEXT->DataBuffer;
    if (DataBuf == NULL)
        DataLen = 0;
    else
        DataLen = 1024;

    IoAcquireRemoveLock(&p_DVCEXT->RemoveLock, Irp);

    DbgPrint("Output Buffer Length : %d\r\n", BufLen);
    DbgPrint("Driver Data Length : %d\r\n", DataLen);
    //
    if (BufLen <= DataLen) {
        ByteTransferred = BufLen; 
    } else {
        ByteTransferred = DataLen;
    }

    RtlCopyMemory(
        Buf, DataBuf, 
        ByteTransferred);

    IoReleaseRemoveLock(&p_DVCEXT->RemoveLock, Irp);
    CompleteRequest(Irp, STATUS_SUCCESS, ByteTransferred);

    DbgPrint("IRP_MJ_READ : End\r\n");
    return STATUS_SUCCESS;
}

Below code segment demos the possible task items in workflow that can support the normal I/O requests to write data from application to driver.

NTSTATUS
PsdoDispatchWrite(
IN PDEVICE_OBJECT DeviceObject,
IN PIRP Irp
)
{
    PVOID Buf; //Buffer provided by user program
    ULONG BufLen; //Buffer length for user provided buffer
    LONGLONG Offset;//Buffer Offset
    PVOID DataBuf; //Buffer provided by Driver
    ULONG DataLen; //Buffer length for Driver Data Buffer
    ULONG ByteTransferred;
    PIO_STACK_LOCATION p_IO_STK;
    PDEVICE_EXTENSION p_DVCEXT;
    NTSTATUS status;

    DbgPrint("IRP_MJ_WRITE : Begin\r\n");

    //Get I/o Stack Location & Device Extension
    p_IO_STK = IoGetCurrentIrpStackLocation(Irp);
    p_DVCEXT = DeviceObject->DeviceExtension;

    //Get User Input Buffer & Length 
    BufLen = p_IO_STK->Parameters.Write.Length;
    Offset = p_IO_STK->Parameters.Read.ByteOffset.QuadPart;
    Buf = (PUCHAR)(Irp->AssociatedIrp.SystemBuffer) + Offset;

    //Get Driver Data Buffer & Length
    DataBuf = p_DVCEXT->DataBuffer;
    DataLen = 1024;

    IoAcquireRemoveLock(&p_DVCEXT->RemoveLock, Irp);

    DbgPrint("Input Buffer Length : %d\r\n", BufLen);
    DbgPrint("Driver Data Length : %d\r\n", DataLen);

    if (BufLen <= DataLen) {
        ByteTransferred = BufLen; 
    } else {
        ByteTransferred = DataLen;
    }

    ByteTransferred = BufLen;
        RtlZeroMemory(
        p_DVCEXT->DataBuffer,
        1024);

    RtlCopyMemory(
        DataBuf,
        Buf, 
        ByteTransferred);

    IoReleaseRemoveLock(&p_DVCEXT->RemoveLock, Irp);
    CompleteRequest(Irp, STATUS_SUCCESS, ByteTransferred);

    DbgPrint("IRP_MJ_WRITE : End\r\n");
    return STATUS_SUCCESS;
}

I/O Support : Direct I/O Mode

Below graph exhibits how Direct I/O mode is supported when data is transferred between client application and driver. Under Direct I/O mode, Memory Manager will create MDL (Memory Descriptor List) to reference the physical address taken by user-provided buffer, all data can be directly referenced via MDL from kernel environment.

In DDK, some MMXxx routines are provided to help you to get MDL that maps to physical address of user-provided buffer.

Below code segment contains the statements that can support data reading under Direct I/O mode. It is achieved by Mmxxx routine, please read it carefully, and you can also find the full code in the zip file. The most important MmXxx you will use in this mode should be - MmGetSystemAddressForMdlSafe, it can obtain the MDL that references the physical address of user-buffer.

NTSTATUS
PsdoDispatchRead(
IN PDEVICE_OBJECT DeviceObject,
IN PIRP Irp
)
{
    PVOID Buf; //Buffer provided by user program
    ULONG BufLen; //Buffer length for user provided buffer
    ULONG Offset;//Buffer Offset
    PVOID DataBuf; //Buffer provided by Driver
    ULONG DataLen; //Buffer length for Driver Data Buffer
    ULONG ByteTransferred;
    PIO_STACK_LOCATION p_IO_STK;
    PDEVICE_EXTENSION p_DVCEXT;

    DbgPrint("IRP_MJ_READ : Begin\r\n");
    //Get I/o Stack Location & Device Extension
    p_IO_STK = IoGetCurrentIrpStackLocation(Irp);
    p_DVCEXT = DeviceObject->DeviceExtension;

    //Get User Output Buffer & Length 
    Buf = MmGetSystemAddressForMdlSafe(
        Irp->MdlAddress, HighPagePriority);

    if (Buf == NULL) {
        DbgPrint("Can't get Virtual Address from MDL\r\n");
        return STATUS_INSUFFICIENT_RESOURCES;
    }
    BufLen = MmGetMdlByteCount(Irp->MdlAddress);
    Offset = MmGetMdlByteOffset(Irp->MdlAddress);

    //Get Driver Data Buffer & Length
    DataBuf = p_DVCEXT->DataBuffer;
    if (DataBuf == NULL)
        DataLen = 0;
    else
        DataLen = 1024;

    IoAcquireRemoveLock(&p_DVCEXT->RemoveLock, Irp);

    DbgPrint("Output Buffer Length : %d\r\n", BufLen);
    DbgPrint("Offset for Buffer in the Memory Page: %d\r\n", Offset);
    DbgPrint("Driver Data Length : %d\r\n", DataLen);
    //
    if (BufLen <= DataLen) {
        ByteTransferred = BufLen; 
    } else {
        ByteTransferred = DataLen;
    }

    RtlCopyMemory(
        Buf, 
        DataBuf, 
        ByteTransferred);

    IoReleaseRemoveLock(&p_DVCEXT->RemoveLock, Irp);
    CompleteRequest(Irp, STATUS_SUCCESS, ByteTransferred);

    DbgPrint("IRP_MJ_READ : End\r\n");
    return STATUS_SUCCESS;
}

Below code segment demos the possible workflow to write data from user application to driver:

NTSTATUS
PsdoDispatchWrite(
IN PDEVICE_OBJECT DeviceObject,
IN PIRP Irp
)
{
    PVOID Buf; //Buffer provided by user program
    ULONG BufLen; //Buffer length for user provided buffer
    ULONG Offset;//Buffer Offset
    PVOID DataBuf; //Buffer provided by Driver
    ULONG DataLen; //Buffer length for Driver Data Buffer
    ULONG ByteTransferred;
    PIO_STACK_LOCATION p_IO_STK;
    PDEVICE_EXTENSION p_DVCEXT;
    NTSTATUS status;

    DbgPrint("IRP_MJ_WRITE : Begin\r\n");

    //Get I/o Stack Location & Device Extension
    p_IO_STK = IoGetCurrentIrpStackLocation(Irp);
    p_DVCEXT = DeviceObject->DeviceExtension;

    //Get User Input Buffer & Length 
    Buf = MmGetSystemAddressForMdlSafe(
        Irp->MdlAddress, HighPagePriority);

    if (Buf == NULL) {
        DbgPrint("Can't get Virtual Address from MDL\r\n");
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    BufLen = MmGetMdlByteCount(Irp->MdlAddress);
    Offset = MmGetMdlByteOffset(Irp->MdlAddress);

    //Get Driver Data Buffer & Length
    DataBuf = p_DVCEXT->DataBuffer;
    DataLen = 1024;

    IoAcquireRemoveLock(&p_DVCEXT->RemoveLock, Irp);

    DbgPrint("Input Buffer Length : %d\r\n", BufLen);
    DbgPrint("Offset for Buffer in the Memory Page: %d\r\n", Offset);
    DbgPrint("Driver Data Length : %d\r\n", DataLen);

    if (BufLen <= DataLen) {
        ByteTransferred = BufLen; 
    } else {
        ByteTransferred = DataLen;
    }

    ByteTransferred = BufLen;
    RtlZeroMemory(
        p_DVCEXT->DataBuffer,
        1024);

    RtlCopyMemory(
        DataBuf,
        Buf, 
        ByteTransferred);

    IoReleaseRemoveLock(&p_DVCEXT->RemoveLock, Irp);
    CompleteRequest(Irp, STATUS_SUCCESS, ByteTransferred);

    DbgPrint("IRP_MJ_WRITE : End\r\n");
    return STATUS_SUCCESS;
}

Contents of the source zip package

The zip file contains below subfolders:

1. Application: it contains the client applications to the Pseudo Driver.
2. bin: it contains the install/uninstall utility for Pseudo Driver.
3. BufferedIO_PW: it is where the Pseudo Driver that employees Buffered I/O mode for read/write resides.
4. DirectIO_PW: it is where the Pseudo Driver that employees Direct I/O Mode for read/write resides.
5. IOCTL_PW: it is where the Pseudo Driver that simply supports user-defined I/O Control Code resides.
6. ShareFiles: it is the common shared library for PnP, Power Management, I/O completion.
7. Install: it contains the source code of install/uninstall utility. (Install utility is directly referenced from DDK's sample, I won't provide redundant copy of it, only the uninstall utility source code is provided in it).

How to build the Pseudo Driver?

1. Unzip the package to some folder you'd like it to be, let's name it ROOT_OF_SOURCE.
2. Select Start->Programs->Development Kits->Windows DDK xxxx.xxxx->Build Environments->Free Build. (This is for free release without debug information in it.)
3. Enter ROOT_OF_SOURCE\SharedFiles subfolder, enter build -cefw, it all goes well, shared library will be generated.
4. Enter ROOT_OF_SOURCE\BufferedIO_PW subfolder, enter build -cefw, it will create Pseudo Driver - BufferDrv.sys. Copy this file into ROOT_OF_SOURCE\BufferedIO_PW\Install if you have made add-in for any new features, the copy is for later driver install.
5. Enter ROOT_OF_SOURCE\DirectIO_PW subfolder, enter build -cefw, it will create Pseudo Driver - DirectDrv.sys. Copy this file into ROOT_OF_SOURCE\DirectIO_PW\Install if you have made add-in for any new features, the copy is for later driver install.
6. Enter ROOT_OF_SOURCE\IOCTL_PW subfolder, enter build -cefw, it will create Pseudo Driver - PseudoDrv.sys. Copy this file into ROOT_OF_SOURCE\IOCTL_PW\Install if you have made add-in for any new features, the copy is for later driver install.

Install Pseudo Driver into system (XP)

1. Unzip the source file, launch DOS prompt-console.
2. Enter into bin subfolder.
3. Execute DevInst.bat, it will automatically install the Pseudo Driver into your system.

Uninstall Pseudo Driver from system (XP)

1. Enter into bin subfolder.
2. Execute DevRemove.bat, it will automatically uninstall all-driver related resources from your system.

Execute client application

You can enter into ROOT_OF_SOURCE\Application subfolder, execute bufferclient.exe, directclient.exe, and clientapp.exe to verify if the three Pseudo Drivers have been installed successfully.

Known Issues

• The install/uninstall of Pseudo Driver won't wok on Window 2000, the root cause might be that the Setup API doesn't work on Window 2000, can't allow driver installed without a physical hardware in it. Can anybody help to resolve it? Many Thanks.
• If you'd like to install/uninstall the Pseudo Driver in Windows 2000, you will need to launch New Hardware Wizard from within Device Manager, and select to install new hardware->Display all hardware->Install from disk->"ROOT_OF_SOURCE\BufferedIO_PW\Install", click on OK button. New Hardware Wizard will install Buffered I/O Pseudo Driver. (This is for Buffered I/O demo driver install. As for Direct I/O, please set source directory to "ROOT_OF_SOURCE\DirectIO_PW\Install").
• Reboot is required if the driver has been reinstalled after un-installation. I don't know why this happened, I hope somebody can inform me. Many Thanks.

Future Directions for Pseudo Driver

1. Fix above issues.
2. WMI support in Pseudo Driver will be added-in.

History

1. Started to create the three Pseudo Drivers on 2002/02/10, finished on 2003/12/28 (I use the rest time for it), released on 2004/10/20 after my book published.

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Note: You must Sign in to post to this message board. FAQ  Message score threshold 1.0 2.0 3.0 4.0 5.0   Search comments     View Normal (slow) Preview (slow) Message View Topic View Thread View Expanded (Supporters only)   Per page 10 25 50 (must logon)     Msgs 1 to 25 of 48 (Total: 48) (Refresh) First Prev Next      Subject  Author  Date    How can you write data to pseudodriver ?   alexnpl  13:33 31 May '06    Hi, is there anyone know how to write data to buffered I/O driver ? I have successfully installed buffered I/O driver to system device in Device Manager. I wanted to test the driver and so I type BufferClient.exe to write data to the driver. Could anyone knows what is the source code in VC++6.0 that can write data to driver from user mode? thx. Alex   [Sign in | View Thread | Get Link]   how to write a filter driver like portmon   Jobjingjo  5:07 16 Feb '06    i want to write a filter driver that can attract to other devices like portmon. ps. i don't understand about writing a (filter/device)driver so much.   [Sign in | View Thread | Get Link] Score: 1.7 (3 votes).   about xp and nt ddk   Govinda R Raj  4:31 15 Feb '06    i am a final year master of computet science student. now i am in my final project work. my project is dealt with retriving the system information. but i need a ddk for developing the driver to retreiving the system fan speed and h/d temprature in xp and nt. i need your advice to get the fan speed with out using drivers. if it is not possible then can you send me the ddk via http://rapidshare.de and please notify me by mail i need your response immedietly my id is srgovinda_ra@yahoo.co.in (because this is very urgent)   [Sign in | View Thread | Get Link]   capture file access events   W M Suleiman  12:45 30 Jan '06    hello i want to capture the file access events like create read write and close, intercept this events and allow or not allow the access . since this is something related to the file system the easyest way to do it will be the IFS kit. but unfortunatly i'm suposed to do that without using the IFS kit. the good news is i'm allowed to use the DDK. so my question is how can i capture these events without using the IFS Kit. thanks in advance Best Regards.   [Sign in | View Thread | Get Link] Score: 1.5 (2 votes).   Why query power state twice?   odawid  7:17 23 Jan '06    Looking at the code I noticed that you are querying the power state twice - why? Wouldn't be sufficient to pass the IRP down to 'NextDeviceObject' and skip the stack location? Or do I overlook something? Oliver   [Sign in | View Thread | Get Link]   PNP Notification   daDude  22:07 20 Dec '05    Hi, Do you know if there's a way to register a callback function to Win PNP manager? This way my app knows when Win PNP manager has done installing/removing a device driver. Please advice, thanks! -Paul   [Sign in | View Thread | Get Link] Score: 2.0 (1 vote).   floppy drive   vasudha_verma  0:28 13 Nov '05    i need to build a floppy device driver.. i read your article.. will dis code be of any help to me.. i mean it does all work like reading and writing.. how should i proceed to write one?? vasudha   [Sign in | View Thread | Get Link] Score: 1.0 (1 vote).   write one?floppy driver   vasudha_verma  0:27 13 Nov '05    i need to build a floppy device driver.. i read your article.. will dis code be of any help to me.. i mean it does all work like reading and writing.. how should i proceed to   [Sign in | View Thread | Get Link]   i can't inst it   horse1997  2:17 11 Nov '05    first, this article help me a lot, thanks but when i execute .\inst\Devinst.bat it can't work well. the console said that' No more data can use.... ' anybody can help me! thanks thank u   [Sign in | View Thread | Get Link] Score: 2.0 (1 vote).   device errors with XP   gearym  12:33 12 Sep '05    I am developing in windows XP, I have successfully compilled and installed the pseudodriver, well at least it gives the message of a succesfull install. Compare device ID: [root\mssmbios] Compare device ID: [*BufIODvc20030801] Compare device ID: [*DirIODvc20030804] Compare device ID: [*PseudoDvc20030801 Found! [*PseudoDvc20030801] Driver Installed successfully. the problem is when I run the test programs in the application directory, i get back error messages that Unable to open PSEUDODEVICE device - error 2 I have used the regedit to see if the driver installed and it does find them? anyone else have this experience. any help would be appreciated   [Sign in | View Thread | Get Link] Score: 1.0 (1 vote).   Re: device errors with XP   pnabuurs  5:13 10 May '06    I have the same problem Does anyone have a sulotion   [Sign in | View Thread | Get Link]   dual input   Anonymous  12:54 28 Apr '05    How would i write a wdm driver for a dual input card?   [Sign in | View Thread | Get Link] Score: 1.0 (2 votes).   compiling clients apps ?   mgmvm  23:52 5 Apr '05    HI..Very good article.. but i can't get the client apps compiling. bufferclient.exe, directclient.exe, and clientapp.exe I am using VC6++. Is there any specific steps that i should do before i attempt to compile them ? thanks a lot !   [Sign in | View Thread | Get Link]   Re: compiling clients apps ?   fishinriver  19:49 14 Jul '06    I just opened the project files with VC6++, and succeeded in compiling all of them in window2000.   [Sign in | View Thread | Get Link]   Help me please!!   BireescuCalin  5:23 4 Apr '05    I have do write an application that has to monitor some traffic on a serial port and the application must determine the time between 2 characters received via COM port. But I can't do that using CreateFile("COM1"...), ReadFile and others APIs which deal with serial communication. Can anyone help me with some advice? I assume I must write some driver... Can anyone give me a point of where I can start? Any help is appreciated. I must say I'm not advanced in driver development. Hello from Calin   [Sign in | View Thread | Get Link] Score: 1.0 (1 vote).   Re: Help me please!!   FrancisT  13:09 1 Aug '05    http://www.naughter.com/serialport.html is for you.   [Sign in | View Thread | Get Link]   How do i assign a drive letter ?   indigoflow  11:14 4 Mar '05    Excelent article! I'm trying to use this code for some customized storage. How do i assign a drive letter so that i can use it as a normal hardrive.   [Sign in | View Thread | Get Link] Score: 1.0 (1 vote).   Re: How do i assign a drive letter ?   fferland237  11:40 23 Mar '05    I would also like to know this. Anyone knows how?   [Sign in | View Thread | Get Link] [Modify | Delete]   Re: How do i assign a drive letter ?   fref213  11:40 23 Mar '05    I would also like to know this. Anyone knows how?   [Sign in | View Thread | Get Link] [Modify | Delete]   Know Issues   Morteza_Ar  11:06 1 Mar '05    Hi, JUST FOR YOUR INFORMATION..... I compiled your code under 2000 AS with ddk 2600 with vc++6. Used your inf file and installed the driver. Everything went well and driver started without rebooting system. I used the user mode application program and there was no problem write and read to driver. Enabling and Disabling of driver thru Device Manager was no problem either.... Regards Morteza   [Sign in | View Thread | Get Link] Score: 2.0 (1 vote).   help me please...........   nandeeshds  7:01 3 Feb '05    hi let me first apreciate you for your great work. i have to use wdm driver for reading video[directly from camera] through the TV tuner card and displaying it in my application. i think i can brief out it in this way. camera -> tv tuner card -> driver[WDM] -> MFC application. i need to dispaly the video in my dialog based MFC application developed in vc6. can you please guide me how i can accomplish this task. i am eagerly waiting for your reply.   [Sign in | View Thread | Get Link]   If it may interist anyone   tcss  8:30 17 Jan '05    there is quite an active list or two about driver development at http://www.osronline.com/page.cfm?name=ListServer[^] very usefull if you can filter out some of the noise.   [Sign in | View Thread | Get Link]   Re: If it may interist anyone   BireescuCalin  5:09 4 Apr '05    Thank you for the link. I found a lot of useful stuff there. Hello from Calin   [Sign in | View Thread | Get Link]   What is the driver supposed to do?   Anonymous  14:07 8 Dec '04    An intoduction which describes what the sample code does is needed. We can't read code if we don't know what it is supposed to do.   [Sign in | View Thread | Get Link] Score: 2.3 (3 votes).   Re: What is the driver supposed to do?   mjtsai  10:23 9 Dec '04    It is a pseudo driver that resides in system kernel space and process simple I/O request from user application, and transfer binary data between them   [Sign in | View Thread | Get Link] Score: 1.5 (2 votes). Last Visit: 7:14 Sunday 15th October, 2006 First Prev Next