OpenCL - Support different platforms with the same binary

Question

Question 1
If I want to build an application with OpenCL support, do I have any guarantees that the OpenCL.lib implementation from my vendor is able to work with all devices from other Vendors? If yes what's the difference between the implementation?

Question 2
Is it possible to use different OpenCL versions in the same application? For example AMD has released a preview driver for OpenCL 2.0 support. On the other hand the lovely company called Nvidia is still trying to ignore everything past OpenCL 1.1. It would be nice if I could write platform specific code in different versions.

Answer 1

1: On Windows, OpenCL.lib is a static wrapper around OpenCL.dll, which is the ICD loader, and exposes all of the available platforms. It is provided by Khronos and redistributed by the OpenCL platform vendors. So go ahead and link to it; it will work with whatever is installed (although if nothing is installed your application won't run because it can't find OpenCL.dll; this is solved other ways).

2: Yes. As long as the ICD loader is the latest, you can get at the newer API on newer platforms / devices. Just don't use new API on old devices; that will crash or worse.