为什么android ndk独立工具链不支持api 19的arm64但android ndk cmake可以 [英] why android ndk standalone toolchain do not support arm64 with api 19 but android ndk cmake does

问题描述

我以前使用android NDK r16b附带的 android.toolchain.cmake 来构建API级别19的arm64-v8a库。

I used to build arm64-v8a lib of api level 19 use android.toolchain.cmake comes with Android NDK r16b like this.

${CMAKE} \
        -DCMAKE_TOOLCHAIN_FILE=${TOOLCHAIN_FILE}                    \
        -DANDROID_NDK=$ANDROID_NDK_HOME                             \
        -DANDROID_ABI="arm64-v8a"                                   \
        -DANDROID_NATIVE_API_LEVEL="android-19"                     \
        -DANDROID_STL="c++_shared"                                  \
        -DANDROID_CPP_FEATURES="rtti exceptions"                    \
        ..

现在我想打包我的lib使用 conan 使用独立工具链。用-arch arm64 和-api 19 制作独立的工具链似乎是不可能的，因为以下命令

Now i want to pack my lib use conan which cross compile android lib use standalone toolchain. Its seems to be impossible to make standalone toolchain with --arch arm64 and --api 19, since the following command

./make_standalone_toolchain.py --arch=arm64 --api=19 --stl=libc++ --install-dir=./test

将失败，并显示错误消息：

will fail with error message:

19小于arm64的最小平台（21）

19 is less than minimum platform for arm64 (21)

有什么办法可以解决

推荐答案

因为没有诸如API 19 ARM64这样的东西。 android-21中添加了64位支持。

Because there's no such thing as API 19 ARM64. 64-bit support was added in android-21.

CMake支持这一点，因为我们的工具链文件是根据当时常用的流行选项建模而成的，它做了。 ndk-build这样做是因为您可以在一个调用中构建多个ABI。在这两种情况下，对于64位目标，构建都会自动将API级别提升至21级。

CMake supports this because our toolchain file was modeled off of a popular option that was commonly used at the time and that's what it did. ndk-build does it because you build multiple ABIs in a single invocation. In both cases, the build automatically pulls the API level up to 21 for 64-bit targets.

独立工具链仅适用于一种体系结构，因此如果您遇到这种情况，它们将产生错误。指定该架构不支持的API级别，因为这可能是一个错误。

Standalone toolchains are for exactly one architecture, so they give an error if you specify an API level that is not supported by that architecture since it was likely a mistake.

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