Why am I getting dynamic initialization not supported for __device__, __constant__, __shared__?

cmake, cuda

Solution

Your `Params` struct is used in the `__constant__` memory definition of `cparams`.

Your `Params` struct contains an element `a` of type `vectorTypef` which is a typedef for the `Vec2` class for `float`. This class has a default constructor, that is assigning elements ultimately of the `Params` struct. This method of assigning data to a `__constant__` region is not legal either in device code or host code.

In device code it's not legal to modify a `__constant__` value at all. In host code (which is what is in view here), `__constant__` values should be assigned using the appropriate API, i.e. `cudaMemcpyToSymbol`. I would recommend that you assign these in your host code explicitly, rather than via a constructor.

So, one possible approach to fix this would be to change your default constructor to an empty one:

public:
   __host__ __device__ Vec2(){ }; // change this line
   T x, y;

(you could also just delete the empty default constructor line)

And, in wrapper.cu (perhaps in `wrapperFunction`), initialize your `Params` `__constant__` struct:

Params hparams;
hparams.a.x = 0.0;
hparams.a.y = 0.0;
cudaMemcpyToSymbol(cparams, &hparams, sizeof(Params));

Problem

I don't understand why am I getting the error `dynamic initialization is not supported for __device__, __constant__, __shared__ variables` when compiling my code. My code looks like wrapper.cu ``` #include "../Params.hpp" __constant__ Params cparams; void wrapperFunction(uint& a) { Params ab; a = 20; } ``` Params.hpp ``` #include "Utils.hpp" typedef struct Params { vectorTypef a; } Params; ``` Utils.hpp ``` #include "Vec2.hpp" typedef unsigned int uint; typedef Vec2<float> vectorTypef; ``` Vec2.hpp ``` template <typename T> class Vec2 { public: Vec2(){ x = 0.0; y = 0.0;} T x, y; }; ``` Building with cmake with the command `CUDA_ADD_EXECUTABLE(test main.cpp cudasrc/wrapper.cu`

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