Can OpenCL running on OSX(Macbook) using CPU?

Hello,

I use a Macbook, it has been installed the OpenCL. The Macbook has CPU:  Intel(R) Core(TM) i7-4850HQ CPU @ 2.30GHz, GPU: GeForce GT 750M, and GPU: Iris Pro. But I can only use the GeForce GT 750M.

I have 2 questions:

Question 1:  If I change the device to the Intel CPU or GPU, it will fail to execute the kernel! Can I use them?

Question 2: Can I use Intel device under OSX? Do I have to reinstall the OpenCL driver or something? But I haven't found a OSX driver.

https://software.intel.com/en-us/articles/opencl-drivers

Thanks!