clGetDeviceIDs

Obtain the list of devices available on a platform.

`cl_int clGetDeviceIDs(`	cl_platform_id `platform`,
	cl_device_type `device_type`,
	cl_uint `num_entries`,
	cl_device_id `*devices`,
	cl_uint `*num_devices)`

Parameters

platform

Refers to the platform ID returned by clGetPlatformIDs or can be NULL. If platform is NULL, the behavior is implementation-defined.

device_type

A bitfield that identifies the type of OpenCL device. The device_type can be used to query specific OpenCL devices or all OpenCL devices available. The valid values for device_type are specified in the following table.

cl_device_type	Description
`CL_DEVICE_TYPE_CPU`	An OpenCL device that is the host processor. The host processor runs the OpenCL implementations and is a single or multi-core CPU.
`CL_DEVICE_TYPE_GPU`	An OpenCL device that is a GPU. By this we mean that the device can also be used to accelerate a 3D API such as OpenGL or DirectX.
`CL_DEVICE_TYPE_ACCELERATOR`	Dedicated OpenCL accelerators (for example the IBM CELL Blade). These devices communicate with the host processor using a peripheral interconnect such as PCIe.
`CL_DEVICE_TYPE_DEFAULT`	The default OpenCL device in the system.
`CL_DEVICE_TYPE_ALL`	All OpenCL devices available in the system.

num_entries

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

devices

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 argument is NULL, this argument is ignored. The number of OpenCL devices returned is the mininum of the value specified by num_entries or the number of OpenCL devices whose type matches device_type.

num_devices

The number of OpenCL devices available that match device_type. If num_devices is NULL, this argument is ignored.

Notes

clGetDeviceIDs may return all or a subset of the actual physical devices present in the platform and that match device_type.

The application can query specific capabilities of the OpenCL device(s) returned by clGetDeviceIDs. This can be used by the application to determine which device(s) to use.

Errors

clGetDeviceIDs returns CL_SUCCESS if the function is executed successfully. Otherwise it returns one of the following:

CL_INVALID_PLATFORM if platform is not a valid platform.
CL_INVALID_DEVICE_TYPE if device_type is not a valid value.
CL_INVALID_VALUE if 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 matched device_type were found.
CL_OUT_OF_RESOURCES if there is a failure to allocate resources required by the OpenCL implementation on the device.
CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the OpenCL implementation on the host.

Specification

OpenCL Specification

Also see

clGetDeviceInfo, clGetPlatformIDs, clCreateContext, Cardinality Diagram

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