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