The D3DDDI_ALLOCATIONINFO structure describes an allocation.


typedef struct _D3DDDI_ALLOCATIONINFO {
  D3DKMT_HANDLE                  hAllocation;
  const VOID                     *pSystemMem;
  VOID                           *pPrivateDriverData;
  UINT                           PrivateDriverDataSize;
  union {
    struct {
      UINT Primary  :1;
      UINT Stereo  :1;
      UINT Reserved  :30;
      UINT Reserved  :31;
    UINT Value;
  } Flags;



[out] A D3DKMT_HANDLE data type that represents a kernel-mode handle to the allocation. This kernel-mode allocation handle is associated with the kernel-mode resource handle (if non-NULL) that the Microsoft Direct3D runtime's pfnAllocateCb function returns in the hKMResource member of the D3DDDICB_ALLOCATE structure. The user-mode display driver can use this kernel-mode allocation handle to reference the allocation in the command buffer.


[in] A pointer to system memory that the Direct3D runtime preallocated. Otherwise, this member is NULL if the allocation is to use video memory.

If the allocation is in system memory, the user-mode display driver should assign the buffer in the pSysMem member of the D3DDDI_SURFACEINFO structure for the resource to pSystemMem. This buffer is specified when the Direct3D runtime calls the user-mode display driver's CreateResource function to create resources.


[in/out] A pointer to buffer that contains optional private data that might be required by the display miniport driver to create the allocation. The display miniport driver can also return data in the buffer. When the contents of the buffer are passed to the display miniport driver, the contents must be in a format that the display miniport driver can process.


[in] The size, in bytes, of the block of private data that pPrivateDriverData points to.


[in] The zero-based identification number of the video present source in a path of a video present network (VidPN) topology if the allocation is for the primary surface. The driver should set VidPnSourceId only for primary allocation types and not for any other type of allocation. If the driver sets VidPnSourceId for any other allocation type in a call to the pfnAllocateCb function, pfnAllocateCb returns D3DDDI_ID_NOTAPPLICABLE.

When the DirectX graphics kernel subsystem initiates the creation of the allocation for the shared primary surface, the display miniport driver can determine the identification number from the VidPnSourceId member of the D3DKMDDI_SHAREDPRIMARYSURFACEDATA structure that the pPrivateDriverData member of the DXGK_ALLOCATIONINFO structure points to.


[in] A union that contains either a structure (with the first three members that are described in the following list) or a 32-bit value (in the Value member) that indentifies the type of allocation:


[in] A UINT that specifies whether the allocation is part of the desktop. Such an allocation is implicitly accessible to the CPU. A primary allocation can be either pinned down at creation or not pinned down at creation.

Setting this member is equivalent to setting the first bit of the 32-bit Value member (0x00000001).


[in] Supported beginning with Windows 8.

A UINT that specifies whether the allocation is a stereo primary allocation. The Stereo member can be set only when the Primary member is set.

Setting this member is equivalent to setting the second bit of the 32-bit Value member (0x00000002).


[in] Supported beginning with Windows 8.

This member is reserved and should be set to zero.

Setting this member to zero is equivalent to setting the remaining 30 bits (0xFFFFFFFC) of the 32-bit Value member to zeros.


[in] This member is reserved and should be set to zero.

Setting this member to zero is equivalent to setting the remaining 31 bits (0xFFFFFFFE) of the 32-bit Value member to zeros.


[in] A 32-bit value that identifies the type of allocation.


When the user-mode display driver sets the Primary bit-field flag in the Flags member of D3DDDI_ALLOCATIONINFO, certain restrictions apply to the DXGK_ALLOCATIONINFO structure in the pAllocationInfo member of the DXGKARG_CREATEALLOCATION structure for the allocation in a call to the display miniport driver's DxgkDdiCreateAllocation function. These restrictions include the following:

  • The allocation is allocated according to preferences; otherwise, the allocation defaults to the supported write segment set, and all of the specified segments in the write segment set must be CPU-accessible.

  • The display miniport driver cannot set the following bit-field flags in the Flags member of DXGK_ALLOCATIONINFO:
    • PermanentSysMem
    • Cached
    • Protected
    • ExistingSysMem
    • ExistingKernelSysMem

The D3DDDI_ID_NOTAPPLICABLE constant is defined in D3dukmdt.h.



Available in Windows Vista and later versions of the Windows operating systems.


D3dukmdt.h (include D3dumddi.h or D3dkmddi.h)

See also




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