IOCTL_ATA_PASS_THROUGH_DIRECT IOCTL (ntddscsi.h)
IOCTL_ATA_PASS_THROUGH_DIRECT allows an application to send almost any ATA command to a target device, with the following restrictions:
If a class driver for the target type of device exists, the application must send the request to the class driver. Thus, an application can send this request directly to the system port driver for a target logical unit only if there is no class driver for the device.
The application must use this request rather than IOCTL_ATA_PASS_THROUGH if the embedded ATA command might require the underlying miniport driver to access memory directly.
If the ATA command requests a data transfer operation, the caller must set up a cache-aligned buffer from which, or into which, the driver can transfer data directly. The caller should ensure the following:
- The data transfer length satisfies the device's I/O alignment requirement; otherwise, this IOCTL fails with STATUS_INVALID_PARAMETER.
- The data transfer length should not be greater than the device's maximum I/O transfer length; otherwise, it is expected that the device will fail the request.
The IOCTL_ATA_PASS_THROUGH_DIRECT request is typically used for transferring large amounts of data (more than 16 KB).
Major code
Input buffer
The buffer at Irp->AssociatedIrp.SystemBuffer contains an ATA_PASS_THROUGH_DIRECT structure that includes a set of task file input registers that indicate the sort of command to be performed. The caller must initialize all the members of this structure except for PathId, TargetId, and Lun, which the port driver fills in. For a data-out command, the DataBuffer member of ATA_PASS_THROUGH_DIRECT must point to a cache-aligned buffer containing the data to be written.
Input buffer length
Parameters.DeviceIoControl.InputBufferLength indicates the size in bytes of the buffer at Irp->AssociatedIrp.SystemBuffer. The value of InputBufferLength is fixed and does not depend on the amount of data transferred. It is equal to sizeof(ATA_PASS_THROUGH_DIRECT). If the size of the buffer is less than sizeof(ATA_PASS_THROUGH_DIRECT), the port driver fails the I/O request and returns an error.
Output buffer
The port driver formats the return data using an ATA_PASS_THROUGH_DIRECT structure that it stores in the buffer at Irp->AssociatedIrp.SystemBuffer.
The port driver stores the transferred data in the cache-aligned buffer pointed to by the DataBuffer member of ATA_PASS_THROUGH_DIRECT.
The port driver fills the CurrentTaskFile member of ATA_PASS_THROUGH_DIRECT with the values present in the device's output registers at the completion of the ATA command. The application is responsible for interpreting the contents of the output registers to determine what errors, if any, were returned by the device.
Output buffer length
The port driver updates the DataTransferLength member of the ATA_PASS_THROUGH_DIRECT structure to indicate the amount of data that was transferred from the device.
Input / Output buffer
None.
Input / Output buffer length
Not applicable.
Status block
The Information member is set to the number of bytes returned in the output buffer at Irp->AssociatedIrp.SystemBuffer. The Status member is set to STATUS_SUCCESS or possibly to STATUS_BUFFER_TOO_SMALL or STATUS_INVALID_PARAMETER if the input Length value in ATA_PASS_THROUGH_DIRECT is improperly set.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows Server 2003 |
| Header | ntddscsi.h (include Ntddscsi.h) |
See also
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