We work with only OpenCL 1.1 support.

The problem of verifying that OpenCL 1.1 support works was always that
drivers that are stuck on 1.1 tend to be so outdated that they are just
broken and fail for others reasons.

However, I'm happy to report that Mesa 18.0.3 together with the open
source amdgpu drivers, which only claim OpenCL 1.1 support, finally
work correctly with Leela Zero. On a Polaris based card, they even
seem faster than the proprietary AMDGPU-PRO drivers.

And this confirms that only OpenCL 1.1 is required.

README.md

@@ -76,9 +76,9 @@ If you prefer a more human style, a network trained from human games is availabl
 https://github.com/KhronosGroup/OpenCL-Headers/tree/master/opencl22/)
 * OpenCL ICD loader (ocl-icd-libopencl1 on Debian/Ubuntu, or reference implementation at https://github.com/KhronosGroup/OpenCL-ICD-Loader)
 * An OpenCL capable device, preferably a very, very fast GPU, with recent
-drivers is strongly recommended (OpenCL 1.2 support should be enough,
-even OpenCL 1.1 might work). If you do not have a GPU, modify config.h in the
-source and remove the line that says "#define USE_OPENCL".
+drivers is strongly recommended (OpenCL 1.1 support is enough).
+If you do not have a GPU, modify config.h in the source and remove
+the line that says "#define USE_OPENCL".
 * The program has been tested on Windows, Linux and macOS.
 
 ## Example of compiling and running - Ubuntu