PoCL-R Reference Android Java Client

This Repository provides a reference application that uses JOCL to provide access to PoCL-R in Java.

Getting started

Prerequisites

In order to build the reference app, a number of programs are needed. Here is a list:

1. Head over to the PortableCL docs and install the required packages.
2. To build JOCL, the use of Maven is also required. On Ubuntu, this can be installed with sudo apt install maven.
3. Android Studio, the version used for development can be found in the "Relevant Versions" subsection. Make sure to use android studio in order to get the android development files also described in the "Relevant Versions" subsection. See "Installing Android packages" for details on how to do this.

Cloning the repository

Clone the repo with its submodules with the following command:

git clone --recurse-submodules [email protected]:cpc/PoCL-R-Reference-Android-Java-Client.git

or initialize submodules after cloning with:

git submodule update --init --recursive

Build JOCL

Go to <source-dir>/external/JOCLRoot/ and run ./build_jocl.sh. This will build JOCL for android with the same android parameters described in the "Relevant Versions" subsection. If you decide to use a different version, you also need to change that in the script.

[note] This script only builds for arm64-v8a

Build the app

Finally, open Android studio and build the app

Relevant versions

Android constantly updates packages and libraries that can break with newer versions. Below is a list of relevent versions currently used:

What	Version	where to check
Android Studio	Flamingo (2022.2.1)	file > settings > appearance & behavior > system settings > updates
JDK	17	file > project structure > SDK Location > gradle settings > gradle JDK
Minimum SDK version	24	android/app/build.gradle > minSdk
Targeted SDK version	33	android/app/build.gradle > targetSdk
Gradle	8.0	file > project structure > project > gradle version
Android Gradle plugin version	8.0.2	file > project structure > project > android gradle plugin version
CMake	3.22.1	android/app/src/main/cpp/CMakeLists.txt > cmake_minimum_required
NDK	25.1.8937393	(android layout in project tab) app/cpp/inlcudes/NDK
C++	17	android/app/build.gradle > cppFlags '-std=c++<version>'

PoCL-R server

In order to use the remote device, a remote device needs to be available. See the PoCL Documentation on how to set up and build the remote server

Tips and Tricks

Check that phone exposes the OpenCL library

Some phones provide a OpenCL library that can be used in C. This library needs to be whitelisted by the vendor. This can be checked like so:

1. adb into the phone
2. run:

   cat /vendor/etc/public.libraries.txt  
   

   and check that libOpenCL.so is there

Installing Android packages

1. install Android Studio
2. install the android sdk from Tools > SDK Manager > SDK Platforms
3. install the android Native Development Kit (NDK) from Tools > SDK Manager > SDK Tools
4. install CMake from Tools > SDK Manager > SDK Tools

Known issues

1. Some OpenCL implementations on Android do not provide all the metadata needed by pocl. A work around is to also have a kernel be built both for the proxy and pocl-r devices.
2. Turning the screen off and on will cause the return buffer in the mendelbrot demo to be filled with zeros.

Authors and acknowledgment

This project is made and maintained by the CPC group.

License

MIT License