C Specification

To create a pipe object, call the function

cl_mem clCreatePipe(
    cl_context context,
    cl_mem_flags flags,
    cl_uint pipe_packet_size,
    cl_uint pipe_max_packets,
    const cl_pipe_properties* properties,
    cl_int* errcode_ret);


  • context is a valid OpenCL context used to create the pipe object.

  • flags is a bit-field that is used to specify allocation and usage information such as the memory arena that should be used to allocate the pipe object and how it will be used. The Memory Flags table describes the possible values for flags. Only CL_​MEM_​READ_​WRITE and CL_​MEM_​HOST_​NO_​ACCESS can be specified when creating a pipe object. If the value specified for flags is 0, the default is used which is CL_​MEM_​READ_​WRITE | CL_​MEM_​HOST_​NO_​ACCESS.

  • pipe_packet_size is the size in bytes of a pipe packet.

  • pipe_max_packets specifies the pipe capacity by specifying the maximum number of packets the pipe can hold.

  • properties specifies a list of properties for the pipe and their corresponding values. Each property name is immediately followed by the corresponding desired value. The list is terminated with 0. Currently, in all OpenCL versions, properties must be NULL.

  • errcode_ret will return an appropriate error code. If errcode_ret is NULL, no error code is returned.


clCreatePipe returns a valid non-zero pipe object and errcode_ret is set to CL_​SUCCESS if the pipe object is created successfully. Otherwise, it returns a NULL value with one of the following error values returned in errcode_ret:

  • CL_​INVALID_​CONTEXT if context is not a valid context.

  • CL_​INVALID_​VALUE if values specified in flags are not as defined above.

  • CL_​INVALID_​VALUE if properties is not NULL.

  • CL_​INVALID_​PIPE_​SIZE if pipe_packet_size is 0 or the pipe_packet_size exceeds CL_​DEVICE_​PIPE_​MAX_​PACKET_​SIZE value specified in the Device Queries table for all devices in context or if pipe_max_packets is 0.

  • CL_​MEM_​OBJECT_​ALLOCATION_​FAILURE if there is a failure to allocate memory for the pipe object.

  • 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.

Pipes follow the same memory consistency model as defined for buffer and image objects. The pipe state i.e. contents of the pipe across kernel-instances (on the same or different devices) is enforced at a synchronization point.

See Also

Document Notes

For more information, see the OpenCL Specification

This page is extracted from the OpenCL Specification. Fixes and changes should be made to the Specification, not directly.

Copyright (c) 2014-2020 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.