C Specification

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

cl_int clGetKernelArgInfo(
    cl_kernel kernel,
    cl_uint arg_indx,
    cl_kernel_arg_info param_name,
    size_t param_value_size,
    void* param_value,
    size_t* param_value_size_ret);

Parameters

  • kernel specifies the kernel object being queried.

  • arg_indx 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 is used to specify the size in bytes of memory pointed to by param_value. This size must be > size of return type as described in the Kernel Argument Queries table.

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

Table 1. List of supported param_names by https://www.khronos.org/registry/OpenCL/specs/2.2/html/OpenCL_API.html#clGetKernelArgInfo
cl_kernel_arg_info Return Type Info. returned in param_value

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_indx. 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_indx. 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_indx. 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_indx. The returned values can be:

CL_​KERNEL_​ARG_​TYPE_​CONST17
CL_​KERNEL_​ARG_​TYPE_​RESTRICT
CL_​KERNEL_​ARG_​TYPE_​VOLATILE18
CL_​KERNEL_​ARG_​TYPE_​PIPE, or
CL_​KERNEL_​ARG_​TYPE_​NONE

CL_​KERNEL_​ARG_​TYPE_​NONE is returned for all parameters passed by value.

CL_​KERNEL_​ARG_​NAME

Missing before version 1.2.

char[]

Returns the name specified for the argument given by arg_indx.

17

CL_​KERNEL_​ARG_​TYPE_​CONST is returned for CL_​KERNEL_​ARG_​TYPE_​QUALIFIER if the argument is declared with the constant address space qualifier.

18

CL_​KERNEL_​ARG_​TYPE_​VOLATILE is returned for CL_​KERNEL_​ARG_​TYPE_​QUALIFIER if the argument is a pointer and the referenced type is declared with the volatile qualifier. For example, a kernel argument declared as global int volatile *x returns CL_​KERNEL_​ARG_​TYPE_​VOLATILE but a kernel argument declared as global int * volatile x does not. Similarly, CL_​KERNEL_​ARG_​TYPE_​CONST is returned if the argument is a pointer and the referenced type is declared with the restrict or const qualifier. For example, a kernel argument declared as global int const *x returns CL_​KERNEL_​ARG_​TYPE_​CONST but a kernel argument declared as global int * const x does not. CL_​KERNEL_​ARG_​TYPE_​RESTRICT will be returned if the pointer type is marked restrict. For example, global int * restrict x returns CL_​KERNEL_​ARG_​TYPE_​RESTRICT.

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

  • CL_​INVALID_​ARG_​INDEX if arg_indx is not a valid argument index.

  • CL_​INVALID_​VALUE if param_name is not valid, or if size in bytes specified by param_value size is < size of return type as described 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_​INVALID_​KERNEL if kernel is a not a valid kernel object.

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.