Not yet, but I can do it as you suggest.

However, I believed that Pyopencl, somewhere buried into some C-wrappers, should be able to make a correct use of the clCreateContextFromType the way I am using it in C (which is working for me in Linux) when invoking it from Python like this:

platform = cl.get_platforms()
context =   cl.Context(dev_type = cl.device_type.GPU,
                                   properties = [(cl.context_properties.PLATFORM,
                                   platform[0])] + get_gl_sharing_context_properties())

but this crashes on Linux with the same segmentation fault.

I tried to reverse-engineer a bit your code: in "", for the class Context, I found this code fragment:

if devices is not None:
            # from device list
            if dev_type is not None:
                raise RuntimeError("one of 'devices' or 'dev_type' "
                                   "must be None",
                                   status_code.INVALID_VALUE, "Context")
            _devices, num_devices = _clobj_list(devices)
            # TODO parameter order? (for clobj_list)
            _handle_error(_lib.create_context(_ctx, c_props,
                                              num_devices, _devices))

            # from device type
            if dev_type is None:
                dev_type = device_type.DEFAULT
            _handle_error(_lib.create_context_from_type(_ctx, c_props,

as far as I can understand, when invoking the Context class by passing the "dev_type" parameter = "cl.device_type.GPU" this should select the "else" case, hence the wrapper "create_context_from_type" which I found defined in "context.cpp":

create_context_from_type(clobj_t *_ctx, const cl_context_properties *props,
                         cl_device_type dev_type)
    // TODO debug print properties
    return c_handle_error([&] {
            *_ctx = new context(
                    dev_type, nullptr, nullptr), false);

Do you think there is any possibility that the latter "pyopencl_call_guarded(clCreateContextFromType, ..etc..)" wrapper in not doing what it is supposed to do? I mean, is it possible that function is not building the correct "clCreateContextFromType" C-function with all necessary arguments?

I am speculating this because, in my C test program, the clCreateContextFromType function works fine in both Linux and Mac.

I agree with you it is still not clear why the simple clCreateContext in C apparently does not work in Linux (at least on my computer).

Erik Zorzin
address: Viale Miramare 235, 34136 Trieste - ITALY
phone: (+39) 3291555703

(sent from my MacBook Air, Erik Zorzin - HOME)

On Tue06 Mar 2018 at 18:23:02, Andreas Kloeckner ( wrote:

Erik Zorzin - HOME <> writes:

> Hi,
> I wrote a similar code in C++ (see code below this email).
> I compile it on Mac this way:
> g++ clgl_interop.cpp -o clgl_interop -framework OpenCL -framework OpenGL -lGLEW -lglfw
> and on Linux this way:
> g++ clgl_interop.cpp -o clgl_interop -lOpenCL -lOpenGL -lGLEW -lglfw
> It looks like the culprit of my problem is the way I create the context.
> On Linux, if I create the context using:
> clCreateContextFromType
> than it works fine.
> Otherwise if in Linux I use:
> clCreateContext
> than it crashes with segmentation fault.

That sounds like an implementation bug then. Have you checked the Nvidia
dev forums or tried reporting this issue (along with your reproducer) to them?