Better explain pyopencl.cffi_cl.LogicError: clGetPlatformIDs failed: <unknown error -1001>

This is documented here. Let's close this issue.

Note that PyOpenCL is no fun (i.e. cannot run code) without an OpenCL device driver (a so-called “ICD”, for “installable client driver”) that provides access to hardware through OpenCL. If you get an error message like pyopencl.cffi_cl.LogicError: clGetPlatformIDs failed: <unknown error -1001>, that means you have no OpenCL drivers installed.

closed

reopened

I meant to leave that open. That message is, with some likelihood, the first thing someone might see out of PyOpenCL, and it's better if it's not unintelligible nonsense.