gr-fosphor install troubles:" Unable to share spectrum VBO into OpenCL context" openCL/GL sharing

Aaron Giles gilesam73 at
Sat Sep 28 14:42:25 UTC 2019

>Yeah, the nVidia driver is annoying ... it used to work and they broke
>it a few years ago and they don't care enough to fix it.
>And since I got a new laptop a few years back, I don't have a nvidia
>card to debug or work around it.

I compared fosphor to the nVidia OpenCL Simple OpenGL Interop example [1]
and noticed that fosphor calls glMapBuffer/glUnmapBuffer to clear the
spectrum vbo between the calls to glBufferData and clCreateFromGLBuffer.
If I eliminate the map/memset/unmap here by removing  the call to
gl_vbo_clear in gl_deferred_init [2], then clCreateFromGLBuffer returns
CL_SUCCESS and fosphor appears to work with CL/GL sharing.  It is not clear
to me if clearing the vbo_spectrum is necessary here, since
cl_queue_clear_buffers later initializes the  mem_spectrum buffer to the
noise floor.

I'm using an nvidia GTX 1650 with version 430.50 of the nvidia drivers
under Linux Mint 18.  A  friend of mine tested the GTX 1060 and also had
 success with this workaround.



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