DXGKDDI_QUERY_CHILD_RELATIONS callback function (dispmprt.h)

Article
02/22/2024

The DxgkDdiQueryChildRelations function enumerates the child devices of a display adapter.

Syntax

DXGKDDI_QUERY_CHILD_RELATIONS DxgkddiQueryChildRelations;

NTSTATUS DxgkddiQueryChildRelations(
  [in]      IN_CONST_PVOID MiniportDeviceContext,
  [in, out] PDXGK_CHILD_DESCRIPTOR ChildRelations,
  [in]      ULONG ChildRelationsSize
)
{...}

Parameters

[in] MiniportDeviceContext

A handle to a context block associated with a display adapter. The display miniport driver's DxgkDdiAddDevice function previously provided this handle to the DirectX graphics kernel subsystem.

[in, out] ChildRelations

A pointer to an array of DXGK_CHILD_DESCRIPTOR structures allocated and zeroed by the caller. The number of elements in the array is one greater than the value returned by DxgkDdiStartDevice in the NumberOfChildren parameter. DxgkDdiQueryChildRelations must fill in all but the last structure in the array with information that describes the child devices of the display adapter. The last structure in the array must remain zeroed.

[in] ChildRelationsSize

The total size, in bytes, of the ChildRelations array including the zeroed structure at the end.

Return value

DxgkDdiQueryChildRelations returns STATUS_SUCCESS if it succeeds; otherwise, it returns one of the error codes defined in Ntstatus.h.

Remarks

All child devices of the display adapter are onboard; monitors and other external devices that connect to the display adapter are not considered child devices.

The display miniport driver must fill in an array of DXGK_CHILD_DESCRIPTOR structures, one for each of the display adapter's children. The array must contain DXGK_CHILD_DESCRIPTOR structures for all current child devices and all potential child devices. For example, if docking a portable computer will result in new video outputs becoming available, those video outputs must have descriptors in the array, even if they are not currently available.

The DxgkDdiQueryChildRelations function should be made pageable.

Requirements

Requirement	Value
Minimum supported client	Available in Windows Vista and later versions of the Windows operating systems.
Target Platform	Desktop
Header	dispmprt.h
IRQL	PASSIVE_LEVEL