RFR: 8370659: [mobile] enable static-libs-image for Android [v2]

[Magnus Ihse Bursie]

On Mon, 5 Jan 2026 09:52:09 GMT, Johan Vos <jvos at openjdk.org> wrote:

>> This PR adds the changes required to compile libjvm.a and the classlibs using the latest upstream code.
>> 
>> Some notes:
>> 
>> To configure/make, the following configuration is recommended:
>> 
>> bash ./configure \
>> --disable-warnings-as-errors \
>> --openjdk-target=aarch64-linux-android \
>> --with-boot-jdk=/opt/jdk-25 \
>> --with-toolchain-path=/opt/android-ndk-r29/toolchains/llvm/prebuilt/linux-x86_64/bin \
>> --with-sysroot=/opt/android-ndk-r29/toolchains/llvm/prebuilt/linux-x86_64/sysroot \
>> --with-toolchain-type=clang
>> 
>> 
>> After configuring the build, run
>> `make static-libs-image`
>> 
>> Note that this requires Android NDK 29, which can be downloaded from https://developer.android.com/ndk/downloads 
>> I only tested this using Linux. Mac/Windows builds may or may not work.
>> 
>> In `make/autoconf/flags-cflags.m4`, the minimum android version is set to 32 (`-target aarch64-linux-android32`). The reason for this is that this version comes with a version of bionic that supports thr_current. This is not strictly needed, but lower versions would require more bionic-specific patches.
>> 
>> I use `#ifdef  __BIONIC__ `and similar in most places where we do "Android" specific checks. The reason for this is that those checks mainly refer to support that is (or isn't) available in Bionic. As such, it is better to compare e.g. bionic with musl and libc unless we are specifically using Android API's
>> 
>> I can provide a sample with a Makefile that validates the build on a real phone, but I think that is not in scope of this PR.
>
> Johan Vos has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
> 
>  - Merge branch 'master' into 8370659-android
>  - Changes required to compile libjvm.a and the classlibs using the latest upstream code.

We have a kind of third level as the OS_ENV; this is currently used on Windows only to separate msys/wsl/cygwin, but it could presumably be re-used (mis-used?) for Android as well. Or, we should introduce a separate OS_SUBTYPE for Android.

Or,perhaps even better, introduce an OS_FAMILY=linux for OS=linux and OS=android. That might be a better fit for the "macOS is BSD" conundrum as well, so we could have OS_FAMILY=bsd and keep OS=macosx or OS=bsd to separate them.

There were a lot of these BIONIC ifdefs. I must admit I don't even know what bionic is; it seems to be the android libc? Maybe we should make it more explicit, like ANDROID_LIBC or ANDROID_BIONIC?

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PR Comment: https://git.openjdk.org/mobile/pull/40#issuecomment-3718609073
PR Comment: https://git.openjdk.org/mobile/pull/40#issuecomment-3718612610