IOCTL_HPMI_QUERY_CAPABILITIES IOCTL (hpmi.h)

Article
05/18/2021

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The IOCTL_HPMI_QUERY_CAPABILITIES command is sent to query features supported by HPMI and Windows services requested by HPMI. Windows will issue this IOCL to HPMI once after a new HPMI driver instance is discovered.

Important Preliminary Information

Major code

IRP_MJ_DEVICE_CONTROL

Input buffer

The AssociatedIrp.SystemBuffer member of the I/O request packet (IRP) points to an initiator-allocated buffer that is used both as the input buffer and the output buffer for the request. On input, this buffer contains a HPMI_QUERY_CAPABILITIES structure in which the version is set to a valid value.

Input buffer length

The Parameters.DeviceIoControl.InputBufferLength member of the IRP's current I/O stack location (IO_STACK_LOCATION) is set to the size in bytes of the buffer that is pointed to by the AssociatedIrp.SystemBuffer member. This size must be greater than or equal to sizeof HPMI_QUERY_CAPABILITIES structure or the request will fail with an error status of STATUS_INVALID_PARAMETER.

Output buffer

If the request completes successfully, the buffer pointed to by the AssociatedIrp.SystemBuffer member contains the requested HPMI capability information. Located at the start of this buffer is a HPMI_QUERY_CAPABILITIES_RESPONSE structure that indicates the type and size of the information in the buffer.

Output buffer length

The Parameters.DeviceIoControl.OutputBufferLength member of the IRP's current I/O stack location is set to the size in bytes of the buffer that is pointed to by the AssociatedIrp.SystemBuffer member. For the request to succeed, this size must be large enough to contain the HPMI capability described in HPMI_QUERY_CAPABILITIES_RESPONSE. Otherwise, the request will fail with error status STATUS_BUFFER_TOO_SMALL.

Input / Output buffer

TBD

Input / Output buffer length

TBD

Status block

Irp->IoStatus.Status is set to STATUS_SUCCESS if the request is successful. Otherwise, Status to the appropriate error condition as a NTSTATUS code, for example STATUS_INVALID_PARAMETER.

Remarks

The IOCTL_HPMI_QUERY_CAPABILITIES request queries the HPMI capabilities or asset information of the power meter. The input HPMI_QUERY_CAPABILITIES structure value specifies the type of capability information to be returned. The data type and contents of the output buffer vary based on the data requested.

This IOCTL may be issued multiple times, HPMI must respond with same
information in HPMI_QUERY_CAPABILITIES_RESPONSE, as a response to all
subsequent IOCTL calls.

Requirements

Requirement	Value
Minimum supported client	Available in Windows 10, version 1709 and later versions of the Windows operating systems.
Header	hpmi.h (include Hpmi.h)