LNK2005 with __declspec(dllexport)

Question

I am programming a simple OpenGL 3D application. If I am running the application on a laptop, the performance is terrible since the internal Intel GPU is selected always and not the more powerfull dedicated AMD GPU.

I did read that I have to inlclude this line to force the application to run on the dedicated GPU:

extern "C" __declspec(dllexport) DWORD AmdPowerXpressRequestHighPerformance = 0x00000001;

However, I get an LNK2005 error that AmdPowerXpressRequestHighPerformanceis already defined in multiple .obj files. I don't know how to fix this and I didn't find this variable name in any of the files that I did include in my application.

If it helps: I am using GLFW3 and GLAD for the OpenGL rendering.

Where exactly did you put this line? Do not put it in a header file. — tkausl, Jan 25 '23 at 16:19
"I didn't find this variable name...": though the compiler found it: what you have is a link-time error. — , Jan 25 '23 at 16:22
Solved! Thank you "tkausl". I did put it in a header file, which was the problem. — Lemonbonbon, Jan 25 '23 at 16:26

score 1 · Answer 1 · answered Jan 25 '23 at 16:27

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Make sure you aren't building GLFW with GLFW_USE_HYBRID_HPG defined, which causes GLFW to export NvOptimusEnablement & AmdPowerXpressRequestHighPerformance itself.

answered Jan 25 '23 at 16:27

genpfault

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score 0 · Accepted Answer · answered Feb 10 '23 at 15:26

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Solved by putting the code in the correct place, as suggested in the comments above.

answered Feb 10 '23 at 15:26

Lemonbonbon

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LNK2005 with __declspec(dllexport)

2 Answers2