Do I have to cross-compile both opencl and clblast for android?

[DavdGao]

Target

I want to build CLBlast for android app with JNI.

Question

I am cross-compiling clblast for android with the following scripts.

• Q1. CLBlast requires OpenCL library, but I don't know If I need to cross-compile opencl library too? Or just build OpenCL on my macbook pro as usual.
• Q2. I'm coding android app with android studio, but I don't know should I use static opencl library libOpenCL.a or libOpenCL.so for CLBlast?

#!/bin/bash

ANDROID_NDK_PATH=/Users/david/Library/Android/sdk/ndk/25.1.8937393/

cmake .. \
	-DCMAKE_SYSTEM_NAME=Android \
	-DCMAKE_SYSTEM_VERSION=33 \
	-DCMAKE_BUILD_TYPE=Release \
	-DCMAKE_ANDROID_ARCH_ABI=arm64-v8a \
	-DCMAKE_ANDROID_NDK=$ANDROID_NDK_PATH \
	-DCMAKE_ANDRFOID_STL_TYPE=gnustl_static \
	-DBUILD_SHARED_LIBS=OFF \
	-DOPENCL_ROOT=/Users/david/Documents/C++/OpenCL-SDK/build_android/OpenCL/include/ \
	-DOPENCL_INCLUDE_DIRS=/Users/david/Documents/C++/OpenCL-SDK/build_android/OpenCL/include/ \
	-DOPENCL_LIBRARIES=/Users/david/Documents/C++/OpenCL-SDK/build_android/OpenCL/libOpenCL.so

cmake --build . --config Release

cmake --install . --prefix install_android

Update 2023/10/25

• I cross-compile OpenCL into both static and shared libraries.
• To cross-compile CLBlast, I try both static and shared libraries for -DOPENCL_LIBRARIES, but only shared libraries work.
• To enable CLBlast in android app, I import both libOpenCL.a and libclblast.a in android project.
  • Note here I use libOpenCL.a rather than libOpenCL.so
• However, in this android project, the function clGetPlatformsIDs in JNI code returns -1001!
  Any suggestions?

[CNugteren]

Regarding Q1, compiling the OpenCL library yourself seems unusual, I would expect that you simply get one from your vendor or find one on your device and link against that one. In any case, something like clGetPlatformsIDs not working isn't a CLBlast problem, so I can't help you any further with that. You would have to look at your vendors manual for OpenCL.

Regarding Q2, I think linking against either a dynamic or static version of CLBlast should work. Just go with your preference or whatever is easiest.

By the way, there is quite some information spread over various issues regarding Android on CLBlast's GitHub issue tracker, as well as some Android documentation at https://github.com/CNugteren/CLBlast/blob/master/doc/installation.md#android-compilation-from-source.

I hope this helps.

[engineer1109]

build OpenCL lib by mesa or KHR code