<html><body><pre>Android NDK x86 (a.k.a. IA-32) instruction set support
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Introduction:
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Android NDK r6 added support for the 'x86' ABI, that allows native code to
run on Android-based devices running on CPUs supporting the IA-32 instruction
set.
The Android x86 ABI itself is fully specified in docs/CPU-ARCH-ABIS.html.
Overview:
---------
Generating x86 machine code is simple: just add 'x86' to your APP_ABI
definition in your Application.mk file, for example:
APP_ABI := armeabi armeabi-v7a x86
Alternatively, since NDK r7, you can use:
APP_ABI := all
will generate machine code for all supported ABIs with this NDK. Doing so
will ensure that your application package contains libraries for all target
ABIs. Note that this has an impact on package size, since each ABI will
correspond to its own set of native libraries built from the same sources.
The default ABI is still 'armeabi', if unspecified in your project.
As you would expect, generated libraries will go into $PROJECT/libs/x86/, and
will be embedded into your .apk under /lib/x86/.
And just like other ABIs, the Android package manager will extract these
libraries on a *compatible* x86-based device automatically at install time,
to put them under <dataPath>/lib, where <dataPath> is the
application's private data directory.
Similarly, the Android Market server is capable of filtering applications
based on the native libraries they embed and your device's target CPU.
Debugging with ndk-gdb should work exactly as described under docs/NDK-GDB.html.
Standalone-toolchain:
---------------------
It is possible to use the x86 toolchain with NDK r6 in stand-alone mode.
See docs/STANDALONE-TOOLCHAIN.html for more details. Briefly speaking,
it is now possible to run:
$NDK/build/tools/make-standalone-toolchain.sh --arch=x86 --install-dir=<path>
The toolchain binaries have the i686-android-linux- prefix.
Compatibility:
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The minimal native API level provided by official Android x86 platform builds
is 9, which corresponds to all the native APIs provided by Android 2.3, i.e.
Gingerbread (note also that no new native APIs were introduced by Honeycomb).
You won't have to change anything to your project files if you target an older
API level: the NDK build script will automatically select the right set of
native platform headers/libraries for you.
Note that, as of today (June 2011), *no* compatible x86 devices exist on the
market.
In particular, while there are various projects which have forked the
official Android open-source tree and added their own x86-specific
customizations, there is absolutely no guarantee that anything generated
with the official Android NDK is going to run on them at the moment.
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