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How to fix error : unrecognized token in Cuda code with nvcc compiler

Asked by HongTu Nguyen on 25 Jul 2013

I wrote this simple code Cuda in Notepad, which I followed in example: http://www.mathworks.com/help/distcomp/executing-cuda-or-ptx-code-on-the-gpu.html

_global_ void add1( double * pi, double c ) { *pi += c; }

>>then I run it on command line in the current directory: nvcc test.cu I received error with a lot of line "error : unrecognized token"

I don't know what is it and how to fix it. Please help me! I use Cuda 5.0, GPU 720M with Cuda-capable 2.0 Thanks!

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HongTu Nguyen

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1 Answer

Answer by Ben Tordoff on 26 Jul 2013
Accepted answer

There are two problems with what you have attempted, one just a typo and the solution to the other will depend on what you are trying to do. First the typo: you are missing an underscore from each side of the global decorator - they should be double underscores:

__global__ void add1(double * pi, double c) 
{ 
  *pi += c; 
}

Now the more important question: what are you trying to achieve? If you are trying to create a PTX file for use with parallel.gpu.CUDAKernel then you need to compile to PTX:

$ nvcc -ptx -arch=sm_20 <filename>.cu

which will procude <filename>.ptx. If you are trying to make a standalone executable then you need to also define a main function as you would for any C++ program.

4 Comments

Ben Tordoff on 29 Jul 2013

Can you post what the code now looks like, the new command you used to compile it and what the error was?

HongTu Nguyen on 29 Jul 2013

Here is my code (I wrote it following the instruction of website: http://www.mathworks.com/help/distcomp/executing-cuda-or-ptx-code-on-the-gpu.html)

__global__ void add1( double * pi, double c ) 
 {
    *pi += c;
 }

I saved it in notepad named: test.cu Then I compiled it in command line, with command:

>>nvcc -ptx test.cu

or I try to use your command:

>>nvcc -ptx -arch=sm_20 test.cu

It has the same error, and the error shows the same picture I've posted.

I do what's wrong? Please help me.

Thanks!

HongTu Nguyen on 29 Jul 2013

Oh...I'm sorry...I'm so silly...

I've created the new notepad file and wrote it again myself.

And it's ok!

I think the old file I copy from website, so it had something wrong :(

Many thanks for your help!

Then...I have question:

**The command: nvcc -ptx -arch=sm_20 < filename.cu>

What "-arch=sm_20" mean?

**And when I compile by command: nvcc -ptx < filenam.cu> (not -arch=sm_20), it still creates test.ptx file.

>>so what is difference?

**And then, when I compile by command: nvcc < filenam.cu>, it has error look like:

Ben Tordoff

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