88 lines
4.4 KiB
Plaintext
88 lines
4.4 KiB
Plaintext
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NOTES FOR ANDROID PLATFORMS
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===========================
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Requirement details
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-------------------
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Beside basic tools like perl and make you'll need to download the Android
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NDK. It's available for Linux, macOS and Windows, but only Linux
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version was actually tested. There is no reason to believe that macOS
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wouldn't work. And as for Windows, it's unclear which "shell" would be
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suitable, MSYS2 might have best chances. NDK version should play lesser
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role, the goal is to support a range of most recent versions.
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Configuration
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-------------
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Android is a naturally cross-compiled target and you can't use ./config.
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You have to use ./Configure and name your target explicitly; there are
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android-arm, android-arm64, android-mips, android-mip64, android-x86
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and android-x86_64 (*MIPS targets are no longer supported with NDK R20+).
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Do not pass --cross-compile-prefix (as you might be tempted), as it will
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be "calculated" automatically based on chosen platform. Though you still
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need to know the prefix to extend your PATH, in order to invoke
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$(CROSS_COMPILE)clang [*gcc on NDK 19 and lower] and company. (Configure
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will fail and give you a hint if you get it wrong.) Apart from PATH
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adjustment you need to set ANDROID_NDK_HOME environment to point at the
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NDK directory. If you're using a side-by-side NDK the path will look
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something like /some/where/android-sdk/ndk/<ver>, and for a standalone
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NDK the path will be something like /some/where/android-ndk-<ver>.
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Both variables are significant at both configuration and compilation times.
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The NDK customarily supports multiple Android API levels, e.g. android-14,
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android-21, etc. By default latest API level is chosen. If you need to
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target an older platform pass the argument -D__ANDROID_API__=N to Configure,
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with N being the numerical value of the target platform version. For example,
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to compile for Android 10 arm64 with a side-by-side NDK r20.0.5594570
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export ANDROID_NDK_HOME=/home/whoever/Android/android-sdk/ndk/20.0.5594570
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PATH=$ANDROID_NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/bin:$ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin:$PATH
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./Configure android-arm64 -D__ANDROID_API__=29
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make
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Older versions of the NDK have GCC under their common prebuilt tools directory, so the bin path
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will be slightly different. EG: to compile for ICS on ARM with NDK 10d:
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export ANDROID_NDK_HOME=/some/where/android-ndk-10d
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PATH=$ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64/bin:$PATH
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./Configure android-arm -D__ANDROID_API__=14
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make
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Caveat lector! Earlier OpenSSL versions relied on additional CROSS_SYSROOT
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variable set to $ANDROID_NDK_HOME/platforms/android-<api>/arch-<arch> to
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appoint headers-n-libraries' location. It's still recognized in order
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to facilitate migration from older projects. However, since API level
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appears in CROSS_SYSROOT value, passing -D__ANDROID_API__=N can be in
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conflict, and mixing the two is therefore not supported. Migration to
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CROSS_SYSROOT-less setup is recommended.
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One can engage clang by adjusting PATH to cover same NDK's clang. Just
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keep in mind that if you miss it, Configure will try to use gcc...
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Also, PATH would need even further adjustment to cover unprefixed, yet
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target-specific, ar and ranlib. It's possible that you don't need to
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bother, if binutils-multiarch is installed on your Linux system.
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Another option is to create so called "standalone toolchain" tailored
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for single specific platform including Android API level, and assign its
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location to ANDROID_NDK_HOME. In such case you have to pass matching
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target name to Configure and shouldn't use -D__ANDROID_API__=N. PATH
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adjustment becomes simpler, $ANDROID_NDK_HOME/bin:$PATH suffices.
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Running tests (on Linux)
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------------------------
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This is not actually supported. Notes are meant rather as inspiration.
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Even though build output targets alien system, it's possible to execute
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test suite on Linux system by employing qemu-user. The trick is static
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linking. Pass -static to Configure, then edit generated Makefile and
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remove occurrences of -ldl and -pie flags. You would also need to pick
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API version that comes with usable static libraries, 42/2=21 used to
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work. Once built, you should be able to
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env EXE_SHELL=qemu-<arch> make test
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If you need to pass additional flag to qemu, quotes are your friend, e.g.
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env EXE_SHELL="qemu-mips64el -cpu MIPS64R6-generic" make test
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