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I am new to Opencl Programming. I have written a matrix multiplication program while compiling it is giving me error My include files are:

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#define CL_USE_DEPRECATED_OPENCL_1_2_APIS
#include <CL/cl.h>
#include <stdbool.h>

But I got an error as:

/usr/bin/ld: /tmp/ccxNPkyU.o: in function `main':
gmm.c:(.text+0x2d3): undefined reference to `clGetPlatformIDs'
/usr/bin/ld: gmm.c:(.text+0x2ef): undefined reference to `clGetPlatformIDs'
/usr/bin/ld: gmm.c:(.text+0x322): undefined reference to `clGetDeviceIDs'
/usr/bin/ld: gmm.c:(.text+0x376): undefined reference to `clCreateContext'
/usr/bin/ld: gmm.c:(.text+0x527): undefined reference to `clCreateCommandQueue'
/usr/bin/ld: gmm.c:(.text+0x5ab): undefined reference to `clCreateProgramWithSource'
/usr/bin/ld: gmm.c:(.text+0x5fc): undefined reference to `clBuildProgram'
/usr/bin/ld: gmm.c:(.text+0x64c): undefined reference to `clGetProgramBuildInfo'
/usr/bin/ld: gmm.c:(.text+0x682): undefined reference to `clCreateKernel'
/usr/bin/ld: gmm.c:(.text+0x6dc): undefined reference to `clCreateBuffer'
/usr/bin/ld: gmm.c:(.text+0x70c): undefined reference to `clCreateBuffer'
/usr/bin/ld: gmm.c:(.text+0x73c): undefined reference to `clCreateBuffer'
/usr/bin/ld: gmm.c:(.text+0x76e): undefined reference to `clCreateBuffer'
/usr/bin/ld: gmm.c:(.text+0x7a0): undefined reference to `clCreateBuffer'
/usr/bin/ld: /tmp/ccxNPkyU.o:gmm.c:(.text+0x7d2): more undefined references to `clCreateBuffer' follow
/usr/bin/ld: /tmp/ccxNPkyU.o: in function `main':
gmm.c:(.text+0x84c): undefined reference to `clSetKernelArg'
/usr/bin/ld: gmm.c:(.text+0x875): undefined reference to `clSetKernelArg'
/usr/bin/ld: gmm.c:(.text+0x89e): undefined reference to `clSetKernelArg'
/usr/bin/ld: gmm.c:(.text+0x8c7): undefined reference to `clSetKernelArg'
/usr/bin/ld: gmm.c:(.text+0x8f8): undefined reference to `clSetKernelArg'
/usr/bin/ld: /tmp/ccxNPkyU.o:gmm.c:(.text+0x929): more undefined references to `clSetKernelArg' follow
/usr/bin/ld: /tmp/ccxNPkyU.o: in function `main':
gmm.c:(.text+0xa58): undefined reference to `clEnqueueReadBuffer'
/usr/bin/ld: gmm.c:(.text+0xa9f): undefined reference to `clEnqueueReadBuffer'
/usr/bin/ld: gmm.c:(.text+0xae6): undefined reference to `clEnqueueReadBuffer'
/usr/bin/ld: gmm.c:(.text+0xb04): undefined reference to `clWaitForEvents'
/usr/bin/ld: gmm.c:(.text+0xb13): undefined reference to `clFinish'
/usr/bin/ld: gmm.c:(.text+0xb3c): undefined reference to `clGetEventProfilingInfo'
/usr/bin/ld: gmm.c:(.text+0xb65): undefined reference to `clGetEventProfilingInfo'
/usr/bin/ld: gmm.c:(.text+0xc9f): undefined reference to `clReleaseMemObject'
/usr/bin/ld: gmm.c:(.text+0xcae): undefined reference to `clReleaseMemObject'
/usr/bin/ld: gmm.c:(.text+0xcbd): undefined reference to `clReleaseMemObject'
/usr/bin/ld: gmm.c:(.text+0xccc): undefined reference to `clReleaseMemObject'
/usr/bin/ld: gmm.c:(.text+0xcdb): undefined reference to `clReleaseMemObject'
/usr/bin/ld: /tmp/ccxNPkyU.o:gmm.c:(.text+0xcea): more undefined references to `clReleaseMemObject' follow
collect2: error: ld returned 1 exit status

I am compiling program by this statement:gcc -o gmmc gmm.c. Can anyone help me

Bhavin Thakar
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    Try `gcc -o gmmc gmmc.c -lOpenCL` to link against `libOpenCL.so` – Ctx Mar 16 '20 at 18:49
  • ```/usr/bin/ld: cannot find -lOpenCL collect2: error: ld returned 1 exit status ``` – Bhavin Thakar Mar 16 '20 at 18:52
  • Looks like your OpenCL library is not installed properly then... Try to look for the directory in which `libOpenCL.so` resides and add this directory with `-L` to the gcc command line. – Ctx Mar 16 '20 at 18:53
  • Can you tell me how to do it – Bhavin Thakar Mar 16 '20 at 18:59
  • Does this answer your question? [What is an undefined reference/unresolved external symbol error and how do I fix it?](https://stackoverflow.com/questions/12573816/what-is-an-undefined-reference-unresolved-external-symbol-error-and-how-do-i-fix) – Zoe Mar 16 '20 at 20:03

1 Answers1

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Link your program with the OpenCL library:

gcc -O2 -Wall -o gmmc gmmc.c -lOpenCL

If this doesn't find the library, you need to pass the path to it:

gcc -O2 -Wall -o gmmc gmmc.c -L/insert/path/here -lOpenCL

where /insert/path/here is the directory that contains libOpenCL.so. You can search a directory for it, e.g.

find /usr/lib -name libOpenCL.so
0xF
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