In my program I want to use a structure containing constant variables and keep it on device all long as the program executes to completion.

I have several header files containing the declaration of 'global' functions and their respective '.cu' files for their definitions. I kept this scheme because it helps me contain similar code in one place. e.g. all the 'device' functions required to complete 'KERNEL_1' are separated from those 'device' functions required to complete 'KERNEL_2' along with kernels definitions.

I had no problems with this scheme during compilation and linking. Until I encountered constant variables. I want to use the same constant variable through all kernels and device functions but it doesn't seem to work.

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                                CODE EXAMPLE
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filename: 'common.h'
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typedef struct {
    double height;
    double weight;
    int age;
} __CONSTANTS;

__constant__ __CONSTANTS d_const;

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filename: main.cu
---------------------------------------------------------------------------
#include "common.h"
#include "gpukernels.h"
int main(int argc, char **argv) {

    __CONSTANTS T;
    T.height   = 1.79;
    T.weight   = 73.2;
    T.age      = 26;

    cudaMemcpyToSymbol(d_consts, &T, sizeof(__CONSTANTS));
    test_kernel <<< 1, 16 >>>();
    cudaDeviceSynchronize();
}

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filename: gpukernels.h
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__global__ void test_kernel();

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filename: gpukernels.cu
---------------------------------------------------------------------------
#include <stdio.h>
#include "gpukernels.h"
#include "common.h"

__global__ void test_kernel() {
    printf("Id: %d, height: %f, weight: %f\n", threadIdx.x, d_const.height, d_const.weight);
}

When I execute this code, the kernel executes, displays the thread ids, but the constant values are displayed as zeros. How can I fix this?