ua_architecture_append_to_library(rt) fails on Android

mojca commented 1 year ago

Description

I'm not able to build the library for Android due to the -rt flag. The compiler reports

ld.lld: error: unable to find library -lrt

The code says:

if(NOT APPLE AND (NOT ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD"))
  ua_architecture_append_to_library(rt)
endif()

but apparently excluding only OpenBSD from the list is not sufficient. Could you perhaps add at least Android to the exclusion list as well?

I tried to check the history, but while the code was touched at several occasions like #1595, it hasn't been significantly changed for quite a while.

Background Information / Reproduction Steps

First extract https://dl.google.com/android/repository/android-ndk-r25b-linux.zip on Ubuntu and then try to build the project.

Used CMake options:

export NDK_PATH=$HOME/android/android-ndk-r25b
cmake -G Ninja \
    -DCMAKE_TOOLCHAIN_FILE=${NDK_PATH}/build/cmake/android.toolchain.cmake \
    -DANDROID_ABI=arm64-v8a \
    -DANDROID_NDK=${NDK_PATH} \
    -DANDROID_PLATFORM=android-24 \
    -DCMAKE_ANDROID_NDK=${NDK_PATH} \
    -DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
    -DCMAKE_SYSTEM_NAME=Android \
    -DCMAKE_SYSTEM_VERSION=24 \
    /path/to/source

Checklist

Please provide the following information:

[x] open62541 Version (release number or git tag): 1.3.2
[ ] Other OPC UA SDKs used (client or server):
[x] Operating system: Linux, building for Android
[ ] Logs (with UA_LOGLEVEL set as low as necessary) attached
[ ] Wireshark network dump attached
[ ] Self-contained code example attached
[ ] Critical issue

ffreality commented 1 year ago

I don't know about RT but select Posix as target platform on Linux (my case ubuntu) CMake. I am working on Unreal Engine plugin and it works.

mojca commented 1 year ago

What do you mean by "select Posix as target platform"?

The relevant code that is causing some problems comes from "if posix" and it starts working for me if I delete ua_architecture_append_to_library(rt): https://github.com/open62541/open62541/blob/c0298a9a6bfcc20cadaf54af640d82cabadfb64e/arch/posix/CMakeLists.txt#L12-L31

mojca commented 1 year ago

Should I try to come up with a github action building for Android that tries to reproduce the build failure?

ffreality commented 1 year ago

I am working on an UE5 client plugin and we use Android NDK for package.

In order to build open62 for Android I built it from Ubuntu and selected target platform as POSIX on CMAKE. I used Posix because it is similiar with Android and I used Ubuntu because there is no cross compile support. My branch was 21 november master branch and I didn't got any error about ua_architecture_append_to_library(rt)

But I disabled some features from CMake because master branch has additional options which 1.3.3 doesn't have. Maybe I could disabled that RT feature, too.

My only error was this and I got it when I tried to package my project as apk. https://github.com/open62541/open62541/issues/5462

We solved it and right now we have no problem about Android and packaging.

open62541 / open62541