In my other thread, I mentioned trouble getting OpenCL working on Linux. Basically, the OpenCL support in the amdgpu-pro driver is looking for a missing libamdoclsc64.so file and appears to not work because of it. The ROCm OpenCL support requires PCI Express 3.0, so I bailed on Linux.
So here I am with Windows, and hashcat is working. However, some other OpenCL applications appear to required Cygwin. And Cygwin-based programs appear to have a similar symptom to my experience on Windows. Except instead of a missing libamdoclsc64.so, It's looking for amdoclsc64.DLL. This file is not present on a Windows install of the AMD drivers (I'm running 17.11.1 on Windows 10 64-bit).
If I run Cygwin clinfo, it reports:
Number of platforms 0
Looking at Procmon, I see that the last thing that clinfo.exe looks for is amdoclsc64.DLL, and fails. Perhaps it's a red herring, but I'd think that AMD not providing amdoclsc64.DLL, which appears to be referenced in amdocl64.dll is a problem.