clGetDeviceIDsFromD3D11KHR

Querying OpenCL Devices Corresponding to Direct3D 11 Devices.

cl_int clGetDeviceIDsFromD3D11KHR ( cl_platform_id platform,
  cl_d3d11_device_source_khr d3d_device_source,
  void *d3d_object,
  cl_d3d11_device_set_khr d3d_device_set,
  cl_uint num_entries,
  cl_device_id *devices,
  cl_uint *num_devices)

Parameters

platform

Refers to the platform ID returned by clGetPlatformIDs.

d3d_device_source

Specifies the type of d3d_object and may be one of the following:.

cl_d3d_device_source_khr Type of d3d_object
CL_D3D11_DEVICE_KHR ID3D11Device *
CL_D3D11_DXGI_ADAPTER_KHR IDXGIAdapter *
d3d_object

Specifies the object whose corresponding OpenCL devices are being queried. The type of d3d_object must be as specified in the table above.

d3d_device_set

Specifies the set of devices to return, and must be one of the following:

cl_d3d_device_set_khr Devices returned in devices
CL_PREFERRED_DEVICES_FOR_D3D11_KHR The OpenCL devices associated with the specified Direct3D object.
CL_ALL_DEVICES_FOR_D3D11_KHR All OpenCL devices which may interoperate with the specified Direct3D object. Performance of sharing data on these devices may be considerably less than on the preferred devices.
num_entries

The number of cl_device_id entries that can be added to devices. If devices is not NULL, the num_entries must be greater than zero.

devices

Returns a list of OpenCL devices found. The cl_device_id values returned in devices can be used to identify a specific OpenCL device. If devices is NULL, this argument is ignored. The number of OpenCL devices returned is the mininum of the value specified by num_entries and the number of OpenCL devices corresponding to d3d_object.

num_devices

Returns the number of OpenCL devices available that correspond to d3d_object. If num_devices is NULL, this argument is ignored.

Description

The OpenCL devices corresponding to a Direct3D 11 device may be queried. The OpenCL devices corresponding to a DXGI adapter may also be queried. The OpenCL devices corresponding to a Direct3D 11 device will be a subset of the OpenCL devices corresponding to the DXGI adapter against which the Direct3D 11 device was created.

Notes

General information about sharing memory objects with Direct3D 11 follows.

The goal of this extension is to provide interoperability between OpenCL and Direct3D 11. This is designed to function analogously to the OpenGL interoperability. If this extension is supported by an implementation, the string cl_khr_d3d11_sharing will be present in the CL_PLATFORM_EXTENSIONS or CL_DEVICE_EXTENSIONS string described in the table of allowed values for param_name for clGetDeviceInfo.

As currently proposed the interfaces for this extension would be provided in cl_d3d11.h.

This section discusses OpenCL functions that allow applications to use Direct3D 11 resources as OpenCL memory objects. This allows efficient sharing of data between OpenCL and Direct3D 11. The OpenCL API may be used to execute kernels that read and/or write memory objects that are also Direct3D 11 resources. An OpenCL image object may be created from a Direct3D 11 texture resource. An OpenCL buffer object may be created from a Direct3D 11 buffer resource. OpenCL memory objects may be created from Direct3D 11 objects if and only if the OpenCL context has been created from a Direct3D 11 device.

An OpenCL memory object created from a Direct3D 11 resource remains valid as long as the corresponding Direct3D 11 resource has not been deleted. If the Direct3D 11 resource is deleted through the Direct3D 11 API, subsequent use of the OpenCL memory object will result in undefined behavior, including but not limited to possible OpenCL errors, data corruption, and program termination.

The successful creation of a cl_context against a Direct3D 11 device specified via the context create parameter CL_CONTEXT_D3D11_DEVICE_KHR will increment the internal Direct3D reference count on the specified Direct3D 11 device. The internal Direct3D reference count on that Direct3D 11 device will be decremented when the OpenCL reference count on the returned OpenCL context drops to zero.

The OpenCL context and corresponding command-queues are dependent on the existence of the Direct3D 11 device from which the OpenCL context was created. If the Direct3D 11 device is deleted through the Direct3D 11 API, subsequent use of the OpenCL context will result in undefined behavior, including but not limited to possible OpenCL errors, data corruption, and program termination.

Properties of Direct3D 11 objects may be queried using clGetMemObjectInfo and clGetImageInfo with param_name CL_MEM_D3D11_RESOURCE_KHR and CL_IMAGE_D3D11_SUBRESOURCE_KHR as described for clGetImageInfo and in the information below about accessing mapped regions of a memory object.

Accessing mapped regions of a memory object

This section describes the behavior of OpenCL commands that access mapped regions of a memory object.

The contents of the region of a memory object and associated memory objects (sub-buffer objects or 1D image buffer objects that overlap this region) mapped for writing (i.e. CL_MAP_WRITE or CL_MAP_WRITE_INVALIDATE_REGION is set in map_flags argument to clEnqueueMapBuffer or clEnqueueMapImage) are considered to be undefined until this region is unmapped.

Multiple commands in command-queues can map a region or overlapping regions of a memory object and associated memory objects (sub-buffer objects or 1D image buffer objects that overlap this region) for reading (i.e. map_flags = CL_MAP_READ). The contents of the regions of a memory object mapped for reading can also be read by kernels and other OpenCL commands (such as clEnqueueCopyBuffer) executing on a device(s).

Mapping (and unmapping) overlapped regions in a memory object and/or associated memory objects (sub-buffer objects or 1D image buffer objects that overlap this region) for writing is an error and will result in CL_INVALID_OPERATION error returned by clEnqueueMapBuffer or clEnqueueMapImage.

If a memory object is currently mapped for writing, the application must ensure that the memory object is unmapped before any enqueued kernels or commands that read from or write to this memory object or any of its associated memory objects (sub-buffer or 1D image buffer objects) or its parent object (if the memory object is a sub-buffer or 1D image buffer object) begin execution; otherwise the behavior is undefined.

If a memory object is currently mapped for reading, the application must ensure that the memory object is unmapped before any enqueued kernels or commands that write to this memory object or any of its associated memory objects (sub-buffer or 1D image buffer objects) or its parent object (if the memory object is a sub-buffer or 1D image buffer object) begin execution; otherwise the behavior is undefined.

Accessing the contents of the memory region referred to by the mapped pointer that has been unmapped is undefined.

The mapped pointer returned by clEnqueueMapBuffer or clEnqueueMapImage can be used as ptr argument value to clEnqueueReadBuffer, clEnqueueWriteBuffer, clEnqueueReadBufferRect, clEnqueueWriteBufferRect, clEnqueueReadImage, and clEnqueueWriteImage, provided the rules described above are adhered to.

Errors

Returns CL_SUCCESS if the function is executed successfully. Otherwise it may return:

  • CL_INVALID_PLATFORM if platform is not a valid platform.
  • CL_INVALID_VALUE if d3d_device_source is not a valid value, d3d_device_set is not a valid value, num_entries is equal to zero and devices is not NULL, or if both num_devices and devices are NULL.
  • CL_DEVICE_NOT_FOUND if no OpenCL devices that correspond to d3d_object were found.

Specification

OpenCL Specification

Also see

cl_khr_d3d11_sharing, clCreateFromD3D11BufferKHR, clCreateFromD3D11Texture2DKHR, clCreateFromD3D11Texture3DKHR, clEnqueueAcquireD3D11ObjectsKHR, clEnqueueReleaseD3D11ObjectsKHR

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