Hello every one,

When I tried to use my vbo with opencl I get a crash when calling clCreateFromGLBuffer

Below a small code that reproduce the issue:

initialisation of the opengl context

sf::ContextSettings settings;
settings.depthBits = 24;
settings.stencilBits = 8;
settings.antialiasingLevel = 2;
sf::Window window(sf::VideoMode(2048, 1024), "GAME",
        sf::Style::Fullscreen, settings);
glewInit();

initialisation of the opencl context

cl_platform_id platform_id = NULL;
cl_device_id device_id = NULL;
cl_uint ret_num_devices;
cl_uint ret_num_platforms;
cl_int ret = clGetPlatformIDs(1, &platform_id, &ret_num_platforms);

ret = clGetDeviceIDs(platform_id, CL_DEVICE_TYPE_GPU, 1, &device_id,
        &ret_num_devices);

cl_context_properties props[] = { CL_GL_CONTEXT_KHR,
        (cl_context_properties) wglGetCurrentContext(), CL_WGL_HDC_KHR,
        (cl_context_properties) wglGetCurrentDC(), CL_CONTEXT_PLATFORM,
        (cl_context_properties) platform_id, 0 };

cl_context context = clCreateContext(props, 1, &device_id, NULL, NULL,
        &ret);

GLuint vboID_m = 0;

Creation of the vertex buffer object

glGenBuffers(1, &vboID_m);
glBindBuffer(GL_ARRAY_BUFFER, vboID_m);
{

    std::vector<float> tmp = { 0., 0., 0., 0., 0., 0., 0., 0., 0. };

    glBufferData(GL_ARRAY_BUFFER, (tmp.size()) * sizeof(float), 0,
    GL_STATIC_DRAW);
    glBufferSubData(GL_ARRAY_BUFFER, 0, tmp.size() * sizeof(float),
            tmp.data());
}
glBindBuffer(GL_ARRAY_BUFFER, 0);

glFlush();

Linkage of the opencl buffer with the opengl vertex buffer object

cl_int status;
clCreateFromGLBuffer(context, CL_MEM_READ_WRITE, vboID_m, &status);
return 0;

Thanks for your help!

Is clCreateFromGLBuffer a valid function pointer? Eg have you tested it for null?

Other than that, I've no idea what your code is doing, but there are two primary reasons why it can crash like this:

- the simpler reason has to do with your function arguments. Is the context valid? You're not running any checks at or around clCreateContext (or any other CL API functions, for that matter)? How can you be sure it succeeds? Add an error check after each call (better yet - wrap each call in a checker macro that you can later define to empty). 

- the more complex reason has to do with the rest of your code. Create a test project. Remove any and all outside factors (multi-threading, prior code not related to the call, etc). If it you've checked everything outlined above and it still crashes, then you're looking at a more serious problem.

Unless you've borked your arguments somewhere, the most likely culprit here is a buffer overflow (eg writing out of bounds) anywhere else in your program, which isn't detected, but thrashes the pointer to clCreateFromGLBuffer. Catching this can be hard. However, for starters, if your IDE supports it, you could try setting a hardware/data breakpoint to clCreateFromGLBuffer after it's been loaded and letting your program run to see if the address is modified. If it is, you'll hopefully know where the problem is.

PS - the code you posted doesn't necessarily reproduce the issue for someone else, because it's not a full program. 

PPS - you're asking for a solution, but your code doesn't seem to be doing any validation/error checking of its own. Without knowing anything about CL, I'm going to go out on a limb and say either your call to clCreateContext is malformed or you have a memory write problem literally anywhere else in your code.

I think I had this issue once, and it was relate to the order of creation CL and OpenGL context. If you've validate all irreversible has mentioned above and all is well, try swapping the order of our context creation.

@irreversible

• Is clCreateFromGLBuffer a valid function pointer? Eg have you tested it for null?

What do you mean by function pointer ? clCreateFromGLBuffer is not a pointer ?!

• - the simpler reason has to do with your function arguments. Is the context valid? You're not running any checks at or around clCreateContext (or any other CL API functions, for that matter)? How can you be sure it succeeds? Add an error check after each call (better yet - wrap each call in a checker macro that you can later define to empty)

I have allready check all the return statment and opengl errors and everything is ok

•  - the more complex reason has to do with the rest of your code. Create a test project. Remove any and all outside factors (multi-threading, prior code not related to the call, etc). If it you've checked everything outlined above and it still crashes, then you're looking at a more serious problem.

It's allready a "test project", I have put that in a main without any other code and it crash.

•  Unless you've borked your arguments somewhere, the most likely culprit here is a buffer overflow (eg writing out of bounds) anywhere else in your program, which isn't detected, but thrashes the pointer to clCreateFromGLBuffer. Catching this can be hard. However, for starters, if your IDE supports it, you could try setting a hardware/data breakpoint to clCreateFromGLBuffer after it's been loaded and letting your program run to see if the address is modified. If it is, you'll hopefully know where the problem is.

No because of the previous point.

@cgrant

• try swapping the order of our context creation.

You mean moving :

cl_platform_id platform_id = NULL;
cl_device_id device_id = NULL;
cl_uint ret_num_devices;
cl_uint ret_num_platforms;
cl_int ret = clGetPlatformIDs(1, &platform_id, &ret_num_platforms);

ret = clGetDeviceIDs(platform_id, CL_DEVICE_TYPE_GPU, 1, &device_id,
        &ret_num_devices);

cl_context_properties props[] = { CL_GL_CONTEXT_KHR,
        (cl_context_properties) wglGetCurrentContext(), CL_WGL_HDC_KHR,
        (cl_context_properties) wglGetCurrentDC(), CL_CONTEXT_PLATFORM,
        (cl_context_properties) platform_id, 0 };

cl_context context = clCreateContext(props, 1, &device_id, NULL, NULL,
        &ret);

GLuint vboID_m = 0;

before : 

sf::ContextSettings settings;
settings.depthBits = 24;
settings.stencilBits = 8;
settings.antialiasingLevel = 2;
sf::Window window(sf::VideoMode(2048, 1024), "GAME",
        sf::Style::Fullscreen, settings);
glewInit();

? Because when I do that I get a CL_INVALID_CONTEXT error.

So I dug up my example code that kinda does the same thing you are doing and I had an explicit note in the code ( granted this is on AMD platform ) to create the OpenCL context prior to creating any GL objects, especially buffered object. I would expect context creation would fail is you did NOT specify a valid OpenGL context handle and device context. I don't know what other objects SMFL creates in the process of its OpenGL context initialization, but it would be good to investigate. Also, how are you retrieving/initializing your OpenCL entry points ? Remember OpenCL follows a similar model to OpenGL. In your example you are using GLEW to initialize your OpenGL entry points (function pointers.) What are you using for OpenCL ? 

• Remember OpenCL follows a similar model to OpenGL. In your example you are using GLEW to initialize your OpenGL entry points (function pointers.) What are you using for OpenCL ? 

Nothing more that what I have written  in my code exemple, I have followed all the tutorial I have found on the web...

15 hours ago, Alex Garcin said:

What do you mean by function pointer ? clCreateFromGLBuffer is not a pointer ?!

if(clCreateFromGLBuffer == NULL) ...

15 hours ago, Alex Garcin said:

I have allready check all the return statment and opengl errors and everything is ok

How? I can't see it in your code.

15 hours ago, Alex Garcin said:

•  - the more complex reason has to do with the rest of your code. Create a test project. Remove any and all outside factors (multi-threading, prior code not related to the call, etc). If it you've checked everything outlined above and it still crashes, then you're looking at a more serious problem.

It's allready a "test project", I have put that in a main without any other code and it crash.

Try stepping through your program an check if anything looks out of the ordinary. Like I said, unless you've malformed one or more of your calls, the culprit is most likely somewhere else in your program. 

Just to have a point of reference, try running your program on a different computer with a different hardware setup. It's unlikely, but not impossible that your driver installation is corrupted etc.

What version is whatever library you use to initialize OpenCL? (update to the latest one)

This might hurt your ego, but if something crashes, then 99.999% of the time it's because of your code . Except when it isn't...

8 hours ago, Andrey OGL_D3D said:

Hi, @Alex Garcin

1) wglGetCurrentContext() != NULL ? wglGetCurrentDC() != NULL ?

2) Try to create OpenGL Context without SMFL(VERY BAD library) or try to use SDL :)))

3) Can you attach your test project ? I can test him.

 

Thanks for your reply,

1) wglGetCurrentContext() != NULL ? wglGetCurrentDC() != NULL ?

None of them are null.


2) Try to create OpenGL Context without SMFL(VERY BAD library) or try to use SDL ))

Will try.


3) Can you attach your test project ? I can test him.

http://garcin.alex.free.fr/partage/test.rar

7 hours ago, irreversible said:

if(clCreateFromGLBuffer == NULL) ...

How? I can't see it in your code.

Try stepping through your program an check if anything looks out of the ordinary. Like I said, unless you've malformed one or more of your calls, the culprit is most likely somewhere else in your program. 

Just to have a point of reference, try running your program on a different computer with a different hardware setup. It's unlikely, but not impossible that your driver installation is corrupted etc.

What version is whatever library you use to initialize OpenCL? (update to the latest one)

This might hurt your ego, but if something crashes, then 99.999% of the time it's because of your code . Except when it isn't...

• if(clCreateFromGLBuffer == NULL) ...

  they aren't null

• How? I can't see it in your code.

  For simplicity I don't have post it.

• Try stepping through your program an check if anything looks out of the ordinary. Like I said, unless you've malformed one or more of your calls, the culprit is most likely somewhere else in your program. 

  As I have said, The small code that I have post in this forum reproduce the issue by itself without any other code addition

• What version is whatever library you use to initialize OpenCL? (update to the latest one)

  4.6.0