Fix cudaErrorInvalidSymbol: Invalid CUDA Symbol Reference

Overview

cudaErrorInvalidSymbol occurs when referencing a non-existent or invalid device symbol. Common with cudaGetSymbolAddress and cudaMemcpyToSymbol.

Error Messages

CUDA error: invalid symbol
cudaErrorInvalidSymbol: invalid device symbol

Common Causes

• •Symbol not declared with __device__ or __constant__
• •Symbol name misspelled
• •Symbol in different compilation unit
• •Separate compilation issues

Solutions

__constant__ float myConstant[256];
__device__ int myDeviceVar;

// For __constant__
cudaMemcpyToSymbol(myConstant, hostData, size);
// For getting address
void* devPtr;
cudaGetSymbolAddress(&devPtr, myDeviceVar);

nvcc -dc file1.cu -o file1.o
nvcc -dc file2.cu -o file2.o
nvcc file1.o file2.o -o program

Prevention Tips

• ✓Declare symbols in header files
• ✓Use extern for shared symbols
• ✓Verify symbol names match exactly

Code Examples

Before (Problematic)

Symbol not device-accessible.

float myConst[256];  // Missing __constant__
cudaMemcpyToSymbol(myConst, data, size);

After (Fixed)

Proper constant memory declaration.

__constant__ float myConst[256];
cudaMemcpyToSymbol(myConst, data, size);

Frequently Asked Questions

Related Errors

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