C Specification

To return information about the arguments of a kernel, call the function

// Provided by CL_VERSION_1_2
cl_int clGetKernelArgInfo(
    cl_kernel kernel,
    cl_uint arg_index,
    cl_kernel_arg_info param_name,
    size_t param_value_size,
    void* param_value,
    size_t* param_value_size_ret);
clGetKernelArgInfo is missing before version 1.2.

Parameters

  • kernel specifies the kernel object being queried.

  • arg_index is the argument index. Arguments to the kernel are referred by indices that go from 0 for the leftmost argument to n - 1, where n is the total number of arguments declared by a kernel.

  • param_name specifies the argument information to query. The list of supported param_name types and the information returned in param_value by clGetKernelArgInfo is described in the Kernel Argument Queries table.

  • param_value is a pointer to memory where the appropriate result being queried is returned. If param_value is NULL, it is ignored.

  • param_value_size specifies the size in bytes of memory pointed to by param_value. This size must be greater than or equal to the size of the return type specified in the Kernel Argument Queries table. If param_value is NULL, it is ignored.

  • param_value_size ret returns the actual size in bytes of data being queried by param_name. If param_value_size_ret is NULL, it is ignored.

Description

Kernel argument information is only available if the program object associated with kernel:

  • is created with clCreateProgramWithBinary and the program executable is built with the -cl-kernel-arg-info and -x spir options specified in the options argument to clBuildProgram or clCompileProgram, if the cl_khr_spir extension is supported; or,

  • is created with clCreateProgramWithSource and the program executable is built with the -cl-kernel-arg-info option specified in the options argument to clBuildProgram or clCompileProgram,

Table 1. List of supported param_names by clGetKernelArgInfo
Kernel Arg Info Return Type Description

CL_KERNEL_ARG_ADDRESS_QUALIFIER

missing before version 1.2.

cl_kernel_arg_address_qualifier

Returns the address qualifier specified for the argument given by arg_index. This can be one of the following values:

CL_KERNEL_ARG_ADDRESS_GLOBAL
CL_KERNEL_ARG_ADDRESS_LOCAL
CL_KERNEL_ARG_ADDRESS_CONSTANT
CL_KERNEL_ARG_ADDRESS_PRIVATE

If no address qualifier is specified, the default address qualifier which is CL_KERNEL_ARG_ADDRESS_PRIVATE is returned.

CL_KERNEL_ARG_ACCESS_QUALIFIER

missing before version 1.2.

cl_kernel_arg_access_qualifier

Returns the access qualifier specified for the argument given by arg_index. This can be one of the following values:

CL_KERNEL_ARG_ACCESS_READ_ONLY
CL_KERNEL_ARG_ACCESS_WRITE_ONLY
CL_KERNEL_ARG_ACCESS_READ_WRITE
CL_KERNEL_ARG_ACCESS_NONE

If argument is not an image type and is not declared with the pipe qualifier, CL_KERNEL_ARG_ACCESS_NONE is returned. If argument is an image type, the access qualifier specified or the default access qualifier is returned.

CL_KERNEL_ARG_TYPE_NAME

missing before version 1.2.

char[]

Returns the type name specified for the argument given by arg_index. The type name returned will be the argument type name as it was declared with any whitespace removed. If argument type name is an unsigned scalar type (i.e. unsigned char, unsigned short, unsigned int, unsigned long), uchar, ushort, uint and ulong will be returned. The argument type name returned does not include any type qualifiers.

CL_KERNEL_ARG_TYPE_QUALIFIER

missing before version 1.2.

cl_kernel_arg_type_qualifier

Returns a bitfield describing one or more type qualifiers specified for the argument given by arg_index. The returned values can be:

CL_KERNEL_ARG_TYPE_CONST
CL_KERNEL_ARG_TYPE_RESTRICT
CL_KERNEL_ARG_TYPE_VOLATILE
CL_KERNEL_ARG_TYPE_PIPE, or
CL_KERNEL_ARG_TYPE_NONE

CL_KERNEL_ARG_TYPE_CONST is returned if the kernel argument is a pointer and the referenced type is declared with the const qualifier. For example, a kernel argument declared as global int const* returns CL_KERNEL_ARG_TYPE_CONST but a kernel argument declared as global int* const does not. Additionally, CL_KERNEL_ARG_TYPE_CONST is returned if the kernel argument is declared with the constant address space qualifier.

CL_KERNEL_ARG_TYPE_RESTRICT is returned if the pointer type is marked restrict. For example, global int* restrict returns CL_KERNEL_ARG_TYPE_RESTRICT.

CL_KERNEL_ARG_TYPE_VOLATILE is returned for CL_KERNEL_ARG_TYPE_QUALIFIER if the kernel argument is a pointer and the referenced type is declared with the volatile qualifier. For example, a kernel argument declared as global int volatile* returns CL_KERNEL_ARG_TYPE_VOLATILE but a kernel argument declared as global int* volatile does not.

CL_KERNEL_ARG_TYPE_NONE is returned for all kernel arguments passed by value.

CL_KERNEL_ARG_NAME

missing before version 1.2.

char[]

Returns the name specified for the argument given by arg_index.

clGetKernelArgInfo returns CL_SUCCESS if the function is executed successfully. Otherwise, it returns one of the following errors:

  • CL_INVALID_KERNEL if kernel is a not a valid kernel object.

  • CL_INVALID_ARG_INDEX if arg_index is not a valid argument index.

  • CL_INVALID_VALUE if param_name is not one of the supported values, or if the size in bytes specified by param_value_size is less than size of the return type specified in the Kernel Argument Queries table and param_value is not NULL.

  • CL_KERNEL_ARG_INFO_NOT_AVAILABLE if the argument information is not available for kernel.

  • 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.

See Also

CL_VERSION_1_2, cl_kernel, cl_kernel_arg_info, cl_uint

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

Copyright 2014-2025 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0