NDK r11 does not work due to toolchain restructure about android-cmake

[DoDoENT]

I've managed to workaround this problem by creating symlink named llvm-3.8 that points to llvm folder and from r10e I've copied folders aarch64-linux-android-clang3.5 and others, renamed them to have suffix clang3.8 and modified their setup.mk to contain only following line:

TOOLCHAIN_VERSION := 4.9

After this I was able to set ANDROID_TOOLCHAIN_NAME variable to aarch64-linux-android-clang3.8 and so on. This worked for me - I was compiling OpenCV 3.0 with clang and libc++ using NDK r11b.

[chenxiaolong]

@osfans You might have to remove the build directory and then rerun CMake. The toolchain file can't seem to change the compiler after the build has already been configured.

[osfans]

@chenxiaolong It works. Thanks! I include your fork of android-cmake in trime.

[adytzs]

@chenxiaolong , I am a newbie in cmake, Can you explain how to "remove the build directory". I got this error

arm-linux-androideabi-gcc: error: armv7-none-linux-androideabi: No such file or directory
arm-linux-androideabi-gcc: error: unrecognized command line option '-target'
arm-linux-androideabi-gcc: error: unrecognized command line option '-fno-integrated-as'
arm-linux-androideabi-gcc: error: unrecognized command line option '-fno-limit-debug-info'

Thanks

[chenxiaolong]

chenxiaolong@6d8525b#commitcomment-16919805 :)

Just pass -DANDROID_TOOLCHAIN_NAME=aarch64-linux-android-clang3.6 or the equivalent toolchain for other ABIs.

[osfans]

@chenxiaolong

-DANDROID_TOOLCHAIN_NAME=arm-linux-androideabi-clang3.6 has errors:

arm-linux-androideabi-g++: error: armv5te-none-linux-androideabi: No such file or directory
arm-linux-androideabi-g++: error: unrecognized command line option '-target'
arm-linux-androideabi-g++: error: unrecognized command line option '-Qunused-arguments'
arm-linux-androideabi-g++: error: unrecognized command line option '-Xclang'
arm-linux-androideabi-g++: error: unrecognized command line option '-mnoexecstack'

[osfans]

@chenxiaolong it works! Thanks!

When -DANDROID_STL=c++_static, there's error:

/usr/local/google/buildbot/out_dirs/aosp-ndk-r11-release/build/tmp/build-5996/build-libc++/ndk/sources/cxx-stl/llvm-libc++/../llvm-libc++abi/libcxxabi/src/cxa_handlers.cpp:112: error: undefined reference to '__atomic_exchange_4'
/usr/local/google/buildbot/out_dirs/aosp-ndk-r11-release/build/tmp/build-5996/build-libc++/ndk/sources/cxx-stl/llvm-libc++/../llvm-libc++abi/libcxxabi/src/cxa_default_handlers.cpp:106: error: undefined reference to '__atomic_exchange_4'
/usr/local/google/buildbot/out_dirs/aosp-ndk-r11-release/build/tmp/build-5996/build-libc++/ndk/sources/cxx-stl/llvm-libc++/../llvm-libc++abi/libcxxabi/src/cxa_default_handlers.cpp:117: error: undefined reference to '__atomic_exchange_4'
clang++: error: linker command failed with exit code 1 (use -v to see invocation)

ndk-build has no error when link c++_static.

[chenxiaolong]

@osfans You're welcome!

Do you have a simple test case that causes the error? I created a simple project and cannot reproduce it: https://github.com/chenxiaolong/ndk_cmake_test I tried armeabi, armeabi-v7a, arm64-v8a, x86, and x86_64 (See test.sh)

[osfans]

@chenxiaolong I create a PR in your repo. It seems I need pass LOCAL_LDLIBS := -latomic somewhere to android-cmake.

[chenxiaolong]

@osfans It looks like that's because CMake is linking the static library in the wrong order. CMake is passing the -latomic parameter before the /opt/android-ndk/.../libc++_static.a parameter to clang++.

This should fix the issue: https://gist.github.com/chenxiaolong/eae919138c5e56b16955d72eaa37041e
I was able to build trime successfully :) https://gist.github.com/chenxiaolong/0df1a2c976dc634ddbe19bcac4624ad3

[osfans]

@chenxiaolong I git pull your r12 commit. I can't make trime with r12 again.
And ndk-build works.

        -DANDROID_TOOLCHAIN_NAME=arm-linux-androideabi-clang \
        -DANDROID_ABI=armeabi \
        -DANDROID_STL=c++_static \
        -DANDROID_NATIVE_API_LEVEL=9

It seems that I cannot choose clang.

[rcdailey]

Looks like r12 restructured things again. Why is google doing this nonsense?

[rpavlik]

I have at least a parser for the release property file in the OSVR fork of this repo

[chenxiaolong]

@osfans I made one more change related to libc++. I am able to successfully build trime now with:

        -DANDROID_TOOLCHAIN_NAME=arm-linux-androideabi-clang \

Commit: chenxiaolong@2522915

[osfans]

@chenxiaolong Thanks. It works.

[rcdailey]

@chenxiaolong I really appreciate your efforts in maintaining the android cmake scripts. The unfortunate issue I see is that we have a lot of smart people investing their free time maintaining these scripts, but they all do it in isolation and the same set of issues have been fixed over and over, but in different ways.

I think it's worth it to start getting people onto 1 repository and pooling fixes together. Would it be unreasonable to pool your efforts into @rpavlik's fork?

[osfans]

Where's rpavlik's fork? I can't find it.

[rpavlik]

The most updated, though not tidiest, branch is here: https://github.com/OSVR/android-cmake/tree/libcxx (under dev, so I haven't pulled things out into pull-requestable-branches yet). I tried to incorporate all the pull requests that I could find that made sense, plus additional changes as needed.

I actually started working in parallel on a more minimal, modern, semi-from-scratch toolchain file that works with, rather than against, current CMake practices, in alt.android.toolchain.cmake in the same directory - it contains some pieces based on the original here (or the modifications I've made to it) but it's simpler and hopefully less fragile. It's incomplete, though enough to build one sample library (jsoncpp) against the NDK r12.

Note also that the folks behind the CrystaX NDK forked some version of this toolchain script and made their own changes - https://github.com/crystax/android-platform-ndk/blob/master/cmake/toolchain.cmake - which I haven't fully ported over into my fork, and vice versa (there are changes that I've incorporated that they don't have). Ideally, I think, that would be the way to go: instead of having to do so much detection/guessing, have the toolchain description be shipped with the NDK, but it appears that might be a dream unless you can use (a currently unreleased version of) the CrystaX NDK.

[DoDoENT]

A colleague of mine created his own android toolchain specifically designed for r11. You can try it our here

[osfans]

@chenxiaolong r13 is out in Archlinux, and trime build breaks again. Will you support it?

trime/jni/OpenCC/src/Common.hpp:26:10: fatal error: 
      'algorithm' file not found
#include <algorithm>
         ^
1 error generated.

[rcdailey]

r13 comes with its own toolchain file. No need to use this anymore.

On Sun, Oct 9, 2016, 8:37 PM osfans [email protected] wrote:

@chenxiaolong https://github.com/chenxiaolong r13 is out and build
breaks again. Will you support it?

trime/jni/OpenCC/src/Common.hpp:26:10: fatal error:
'algorithm' file not found
#include
^
1 error generated.

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[osfans]

Yes, it works!
-DCMAKE_TOOLCHAIN_FILE=${ANDROID_NDK}/build/cmake/android.toolchain.cmake

[osfans]

@rcdailey
I have to -DLIBRARY_OUTPUT_PATH=../libs/armeabi/ to install jni libs.
Any other solutions?

[rcdailey]

I use a custom command in cmake to copy my binary to that directory so ant
can find it.

On Tue, Oct 11, 2016, 12:04 AM osfans [email protected] wrote:

@rcdailey https://github.com/rcdailey
I have to -DLIBRARY_OUTPUT_PATH=../libs/armeabi/ to install jni libs.
Any other solutions?

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[wo4li2wang]

@chenxiaolong It works ,3Q