The IO_ERROR_LOG_PACKET structure serves as the header for an error log entry.


typedef struct _IO_ERROR_LOG_PACKET {
  UCHAR         MajorFunctionCode;
  UCHAR         RetryCount;
  USHORT        DumpDataSize;
  USHORT        NumberOfStrings;
  USHORT        StringOffset;
  USHORT        EventCategory;
  NTSTATUS      ErrorCode;
  ULONG         UniqueErrorValue;
  NTSTATUS      FinalStatus;
  ULONG         SequenceNumber;
  ULONG         IoControlCode;
  LARGE_INTEGER DeviceOffset;
  ULONG         DumpData[1];



Indicates the IRP_MJ_XXX major function code of the IRP the driver was handling when the error occurred. Setting this value is optional.


Indicates the number of times the driver has retried the operation and encountered this error. Use zero to indicate the driver attempted the operation once, or add one for each retry beyond the initial attempt.


Indicates the size, in bytes, of the variable-length DumpData member of this structure. The specified value must be a multiple of sizeof(ULONG).


Indicates the number of insertion strings the driver will supply with this error log entry. Drivers set this value to zero for errors that need no insertion strings. The Event Viewer uses these strings to fill in the "%2" through "%n" entries in the string template for this error code.

The null-terminated Unicode strings themselves follow the IO_ERROR_LOG_PACKET structure in memory.


Indicates the offset, in bytes, from the beginning of the structure, at which any driver-supplied insertion string data begins. Normally this will be sizeof(IO_ERROR_LOG_PACKET) plus the value of the DumpDataSize member. If there are no driver-supplied insertion strings, StringOffset can be zero.


Specifies the event category for the error. A driver specifies the event categories it supports and corresponding descriptive strings in its message catalog. The Event Viewer displays the descriptive string as the Category value for the error.


Specifies the type of error. The Event Viewer uses the error code to determine which string to display as the Description value for the error. The Event Viewer takes the string template for the error supplied in the driver's message catalog, replaces "%1" in the template with the name of the driver's device object, and replaces "%2" through "%n" with the insertion strings supplied with the error log entry.

ErrorCode is a system-defined or driver-defined constant; see Logging Errors for more information.


A driver-specific value that indicates where the error was detected in the driver. Setting this value is optional.


Specifies the NTSTATUS value to be returned for the operation that triggered the error. Setting this value is optional.


Specifies a driver-assigned sequence number for the current IRP, which should be constant for the life of a given request. Setting this value is optional.


For an IRP_MJ_DEVICE_CONTROL or IRP_MJ_INTERNAL_DEVICE_CONTROL IRP, this member specifies the I/O control code for the request that trigged the error. Otherwise, this value is zero. Setting this value is optional.


Specifies the driver-specified offset into the device where the error occurred. Setting this value is optional.


A variable-size array that can be used to store driver-specific binary data, such as register values or any other information useful in identifying the cause of the error. Drivers must specify the size, in bytes, of the array in the DumpDataSize member of this structure.


Drivers use the IoAllocateErrorLogEntry routine to allocate an error log entry. The IO_ERROR_LOG_PACKET structure serves as the header for the returned buffer. It is followed in memory by any insertion strings for the log entry.

Note that the I/O manager itself inserts some information into the system error log, such as the name of the device and driver. The I/O manager reserves 80 bytes to hold this information. If the size of this information exceeds 80 bytes, then the I/O manager truncates the driver's insertion strings as necessary.

For more information about how to use this structure, see Logging Errors.



Wdm.h (include Wdm.h, Ntddk.h, or Ntifs.h)

See also




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