# Gr-fosphor. builds OK, throws runtime error

**URL:** <https://www.ruby-forum.com/t/gr-fosphor-builds-ok-throws-runtime-error/231734>\
**Category:** GNU Radio\
**Created:** [August 27, 2014, 6:36am UTC](https://www.ruby-forum.com/t/gr-fosphor-builds-ok-throws-runtime-error/231734 "2014-08-27T06:36:24Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [August 27, 2014, 6:36am UTC](https://www.ruby-forum.com/t/gr-fosphor-builds-ok-throws-runtime-error/231734/1 "2014-08-27T06:36:24Z")

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Ubuntu 14.04.  
Have updated to gnuradio 3.7.5git-194-g76a271ac, seems to run fine.

I rebuilt / reinstalled gr-fosphor. No problems with the build. The  
location of Nvidia’s OpenCL library  
changed from Ubuntu 13.10 to 14.04. The cmake command was:

cmake …/  
-DOPENCL\_LIBRARY=/usr/lib/x86\_64-linux-gnu/libnvidia-opencl.so.1

cmake and make complete successfully.

The QT fosphor block shows up in Gnuradio Companion OK. When trying to  
run, I get the following error:

from gnuradio import fosphor  
File  
“/usr/local/lib/python2.7/dist-packages/gnuradio/fosphor/ **init**.py”,  
line  
45, in   
from fosphor\_swig import \*  
File  
“/usr/local/lib/python2.7/dist-packages/gnuradio/fosphor/fosphor\_swig.py”,  
line 28, in   
\_fosphor\_swig = swig\_import\_helper()  
File  
“/usr/local/lib/python2.7/dist-packages/gnuradio/fosphor/fosphor\_swig.py”,  
line 24, in swig\_import\_helper  
\_mod = imp.load\_module(’\_fosphor\_swig’, fp, pathname, description)  
ImportError: /usr/local/lib/libgnuradio-fosphor-3.7.0git.so.0.0.0:  
undefined symbol: clBuildProgram

The version of gr-fosphor (which git tells me is the latest) is:  
Revision: 9aea19a  
Author: Sylvain M.  
Date: 2014-07-24 22:34:07  
fosphor: Allow operation without CL/GL sharing extension

Any advice?

– Tom, N5EG

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**Author:** ![Tom\_McDermott](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/9fc29f/32.png) [@Tom\_McDermott](https://www.ruby-forum.com/u/Tom_McDermott)\
**Post date:** [August 27, 2014, 7:55am UTC](https://www.ruby-forum.com/t/gr-fosphor-builds-ok-throws-runtime-error/231734/2 "2014-08-27T07:55:30Z")

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> cmake ../ -DOPENCL\_LIBRARY=/usr/lib/x86\_64-linux-gnu/libnvidia-opencl.so.1

That’s not correct.

libnvidia-opencl.so.1 is the backend driver. You need to link against  
the ICD loader which should be named libOpenCL.so

Cheers,

```
Sylvain

```

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<div class="post-metadata">

**Author:** ![Tom\_McDermott](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/9fc29f/32.png) [@Tom\_McDermott](https://www.ruby-forum.com/u/Tom_McDermott)\
**Post date:** [August 27, 2014, 1:25pm UTC](https://www.ruby-forum.com/t/gr-fosphor-builds-ok-throws-runtime-error/231734/3 "2014-08-27T13:25:11Z")

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Thank you, Manaut. That indeed was my problem, it runs fine making  
that  
change.

gr-fosphor is such an incredibly useful tool, it’s painful to do  
without.

– Tom, N5EG

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<div class="post-metadata">

**Author:** ![Tom\_McDermott](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/9fc29f/32.png) [@Tom\_McDermott](https://www.ruby-forum.com/u/Tom_McDermott)\
**Post date:** [August 27, 2014, 1:30pm UTC](https://www.ruby-forum.com/t/gr-fosphor-builds-ok-throws-runtime-error/231734/4 "2014-08-27T13:30:40Z")

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Thank you Sylvain. Apologies for misspelling your name.

– Tom, N5EG