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POProblems with creating a CUDA shared library and libpthread
 

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  1. POProblems with creating a CUDA shared library and libpthread
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    <p>I am currently trying to create a library with CUDA routines but I am running into trouble. I will explain my problems using a rather minimal example, my actual library will be larger.</p> <p>I have successfully written <code>test.cu</code>, a source file containing a <code>__global__</code> CUDA function and a wrapper around it (to allocate and copy memory). I can also successfully compile this file into a shared library using the following commands:</p> <pre><code>nvcc -c test.cu -o test.o -lpthread -lrt -lcuda -lcudart -Xcompiler -fPIC gcc -m64 -shared -fPIC -o libtest.so test.o -lpthread -lrt -lcuda -lcudart -L/opt/cuda/lib64 </code></pre> <p>The resulting <code>libtest.so</code> exports all my needed symbols.</p> <p>I now compile my purely C <code>main.c</code> and link it against my library:</p> <pre><code>gcc -std=c99 main.c -o main -lpthread -ltest -L. </code></pre> <p>This step is also successful, but upon executing <code>./main</code> all CUDA functions that are called return an error:</p> <pre><code>test.cu:17:cError(): cudaGetDeviceCount: [38] no CUDA-capable device is detected test.cu:17:cError(): cudaMalloc: [38] no CUDA-capable device is detected test.cu:17:cError(): cudaMemcpy: [38] no CUDA-capable device is detected test.cu:17:cError(): cudaMemcpy: [38] no CUDA-capable device is detected test.cu:17:cError(): cudaFree: [38] no CUDA-capable device is detected </code></pre> <p>(Error messages are created through a debugging function of my own)</p> <p>During my initial steps I encountered the exact same problem, as I was directly creating an executable from <code>test.cu</code>, because I forgot to link against libpthread (<code>-lpthread</code>). But, as you can see above, I have linked all source files against libpthread. According to <code>ldd</code>, both <code>libtest.so</code> and <code>main</code> depend on libpthread, as it should be.</p> <p>I am using CUDA 5 (yes, I do realize it is a beta) with gcc 4.6.3 and nvidia driver version 302.06.03 on ArchLinux.</p> <p>Some help in solving this problem would be more than appreciated!</p>
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    1. COAre you sure this isn't just a thread affinity problem? Whichever thread creates/holds the context on the device is the only one which can use the device. If you want multiple threads to use the context, you will need to use the context migration API.
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      1. POProblems with creating a CUDA shared library and libpthread
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    2. COAs I am not forking or anything, there should only be a single thread, if I am not vastly mistaken.
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      1. POProblems with creating a CUDA shared library and libpthread
      1. USSarek
    3. COSorry for asking the obvious, but do you have a CUDA capable device? And have you checked that other CUDA code works ok with the same toolkit/driver?
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