Is there an option to create a shared library for Android applications?

gecng commented at 6:05 am on May 17, 2019: none

I use ./configure --enable-jni --enable-experimental --enable-module-schnorr --enable-module-ecdh and get one secp256k1.so files.but there are many different CPU architectures in android like armeabi ,rmeabi-v7a,arm64-v8a ,x86 . Could you please tell me how should I do to create .so files for different CPU architectures. Thanks

gecng commented at 6:18 am on May 17, 2019: none

when I use System.loadLibrary("javasecp256k1") ， it throws exception java.lang.UnsatisfiedLinkError: dlopen failed: “/data/app/com.wallet.locker-Gpfu8hdv5zMz363H3eJC8Q==/lib/arm/libjavasecp256k1.so” is 64-bit instead of 32-bit.

sipa commented at 8:11 pm on May 18, 2019: contributor

I don’t much about Android, but generally I would expect you need a separate build/.so per architecture, and then ship the right one for the used architecture.

gecng commented at 3:08 am on May 19, 2019: none

I don’t much about Android, but generally I would expect you need a separate build/.so per architecture, and then ship the right one for the used architecture.

yes,I really need a separate build/.so per architecture, but I don’t know the way to build it

real-or-random commented at 6:39 am on May 20, 2019: contributor

configure has a --host option for cross compilation.

real-or-random commented at 4:40 pm on May 24, 2019: contributor

For reference, I can build this for example by installing Android NDK 19 and then using

0export PATH="$PATH:/opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin"
1./configure --enable-ecmult-static-precomputation --enable-experimental --with-bignum=no --with-asm=arm --host=arm-linux-androideabi CC=armv7a-linux-androideabi21-clang CFLAGS="-mthumb -march=armv7-a" CCASFLAGS="-Wa,-mthumb -Wa,-march=armv7-a"

See https://developer.android.com/ndk/guides/standalone_toolchain for more information, e.g., the right flags for other targets.

gecng commented at 5:08 am on May 27, 2019: none

For reference, I can build this for example by installing Android NDK 19 and then using
0export PATH="$PATH:/opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin"
1./configure --enable-ecmult-static-precomputation --enable-experimental --with-bignum=no --with-asm=arm --host=arm-linux-androideabi CC=armv7a-linux-androideabi21-clang CFLAGS="-mthumb -march=armv7-a" CCASFLAGS="-Wa,-mthumb -Wa,-march=armv7-a"
See https://developer.android.com/ndk/guides/standalone_toolchain for more information, e.g., the right flags for other targets.

thank you very much , i use this way and has solved my problem.

gecng closed this on May 27, 2019

real-or-random cross-referenced this on Dec 5, 2019 from issue travis: Add some arm builds by MarcoFalke

strongpower commented at 3:13 am on April 3, 2020: none

Hi @real-or-random, how to build library for all Android arch? One library file for all Android platform?

real-or-random commented at 8:06 am on April 3, 2020: contributor

Hi, I don’t think that’s possible. But it’s possible to build different libaries for the different platforms: https://developer.android.com/ndk/guides/other_build_systems#autoconf And then I’m sure there’s also a way to ship all of these builds in different builds of your app but I have no idea how this works.

Maybe we should some instructions for Android.

strongpower commented at 10:02 am on April 3, 2020: none

Thanks for reply!

Maybe we should some instructions for Android.

That would be great!

real-or-random cross-referenced this on Apr 6, 2020 from issue Add better build documentation by gmaxwell

kroggen commented at 4:29 pm on November 20, 2020: none

I use this script to build for Android:

 0#!/bin/bash
 1
 2set -e
 3
 4if [ -z "$ANDROID_NDK" ]; then
 5   echo "export the ANDROID_NDK environment variable"
 6   exit 1
 7fi
 8
 9# Only choose one of these, depending on your build machine...
10export TOOLCHAIN=$ANDROID_NDK/toolchains/llvm/prebuilt/darwin-x86_64
11#export TOOLCHAIN=$ANDROID_NDK/toolchains/llvm/prebuilt/linux-x86_64
12
13# create links to some toolchains binaries (https://github.com/android/ndk/issues/1324)
14cd $TOOLCHAIN/bin/
15for source in arm-linux-androideabi-*
16do
17    dest=${source/arm/armv7a}
18    ln -sf $source $dest
19done
20cd -
21
22# Set this to your minSdkVersion.
23export API=21
24
25pwd=`pwd`
26
27buildit()
28{
29    abi=$1
30    target=$2
31
32    echo ""
33    echo "-------------------------------------------------------------------------------"
34    echo " Compiling for $abi"
35    echo "-------------------------------------------------------------------------------"
36
37    export TARGET=$target
38
39    # Configure and build.
40    export AR=$TOOLCHAIN/bin/$TARGET-ar
41    export AS=$TOOLCHAIN/bin/$TARGET-as
42    export CC=$TOOLCHAIN/bin/$TARGET$API-clang
43    export CXX=$TOOLCHAIN/bin/$TARGET$API-clang++
44    export LD=$TOOLCHAIN/bin/$TARGET-ld
45    export RANLIB=$TOOLCHAIN/bin/$TARGET-ranlib
46    export STRIP=$TOOLCHAIN/bin/$TARGET-strip
47
48    ./configure --prefix="$pwd/android/$abi" --host=$TARGET --disable-benchmark
49
50    make clean
51    make
52    make install
53}
54
55buildit armeabi-v7a armv7a-linux-androideabi
56buildit arm64-v8a   aarch64-linux-android
57buildit x86         i686-linux-android
58buildit x86-64      x86_64-linux-android
59
60make clean
61
62echo "done. the files are in the android folder"

Save it in the repo’s root and run it:

0./make-android

real-or-random commented at 9:00 am on November 23, 2020: contributor

@kroggen Thanks for sharing. That’s really helpful. Can we add this to our repo once we solve #622?

kroggen commented at 3:44 pm on November 23, 2020: none

Yep, feel free

real-or-random cross-referenced this on Jan 2, 2021 from issue Autoconf improvements by real-or-random

real-or-random referenced this in commit f2d9aeae6d on Jan 12, 2021

real-or-random cross-referenced this on May 29, 2022 from issue How to compile Secp256K1 .a static library for different architectures by BatterMan-Li

hebasto commented at 8:04 pm on June 28, 2022: member

#1113 (comment) could be related.

Is there an option to create a shared library for Android applications? #621