Quick guide on how to compile v8 8.4-lkgr for Android on Ubuntu in one copy/paste script. I use this script regularly, so it is well tested.
If you are looking for some already pre-compiled ready-to-use v8 version, you can find them here.
# Install git:
sudo apt install git
# Install depot tools
Follow instructions https://v8.dev/docs/source-code.
# Fetch v8 source code.
# Use the branch of your choice. In will use 8.4-lkgr (last known good release).
# I'd advise always using -lkgr branches
fetch v8
cd v8
git pull
git checkout 8.4-lkgr
# Enter v8 folder.
cd v8
# Install all dependencies, ndk, sdk, etc.
# This may take a while. It downloads android tools: sdk+ndk, etc.
build/install-build-deps-android.sh
# Set android target. This op will take some time, ndk alone is +1Gb
echo "target_os = ['android']" >> ../.gclient && gclient sync
# Generate compilation target:
# Change android_arm.release to the folder name of your choice, in this
# case: out.gn/android_arm.release
#
# Use this to compile for arm/arm64
tools/dev/v8gen.py arm.release
# Use this to compile for x86
tools/dev/v8gen.py ia32.release
# Edit gn configuration file:
# I’d recommend disabling icu support, and set
# symbol_level=0 for faster compilation and thinner
# output libs. You can get the whole list of
# compilation options by executing:
# `gn args out.gn/android_arm.release —-list`
#
# Optionally set `target_cpu="arm64"` or `target_cpu="x86"` (if ia32 was used)
vi out.gn/android_arm.release/args.gn
# This is my file contents:
android_unstripped_runtime_outputs = false
is_component_build = false
is_debug = false
symbol_level = 1
target_cpu = "arm"
target_os = "android"
use_goma = false
use_custom_libcxx = false
use_custom_libcxx_for_host = false
v8_target_cpu = "arm"
v8_use_external_startup_data = false
v8_enable_i18n_support= false
v8_android_log_stdout = true
v8_static_library = true
v8_monolithic = true
v8_enable_pointer_compression = false
# to compile arm64, just change target_cpu and v8_target_cpu to arm64
# Compile target:
# This may take up to 1 hour depending on your setup.
# Optionally use a -j value suitable for your system.
ninja -C out.gn/android_arm.release v8_monolithic
# Fat lib file has been generated by v8_monolithic parameter at
# out.gn/<e.g. android_arm.release>/obj/libv8_monolithic.a
# source headers, for inspector compilation.
mkdir -p src/base/platform
mkdir -p src/common
mkdir -p src/inspector
mkdir -p src/json
mkdir -p src/utils
mkdir -p src/init
cp -R ../../../../src/common/*.h ./src/common
cp -R ../../../../src/base/*.h ./src/base
cp -R ../../../../src/base/platform/*.h ./src/base/platform
cp -R ../../../../src/inspector/*.h ./src/inspector
cp -R ../../../../src/json/*.h ./src/json
cp -R ../../../../src/utils/*.h ./src/utils
cp -R ../../../../src/init/*.h ./src/init
# copy v8 compilation header files:
cp -R ../../../../include ./
# For compilation on Android, always use the same ndk as
# `gclient sync` downloaded.
# Enjoy v8 embedded in an Android app
Compile for Android emulator
tools/dev/v8gen.py gen ia32.release
# edit out.gn/ia32.release/args.gn, to contain the following:
is_debug = false
target_cpu = "x86"
use_goma = false
target_os = "android"
v8_use_external_startup_data = false
v8_enable_i18n_support = false
v8_monolithic = true
Quantum observations 
Hi
I needed to built v8 with NDK version 21 which was different than what gclient sync downloaded. So i changed the ndk paths used by v8 to refer to NDK version 21 paths. After building for arm64 and x86_64 and using libv8_monolith.a files in android studio, the project runs successfully.
But for 32-bit devices ( i.e. arm and x86), though the build is successful, the android project crashes. I am not able to find any specific argument that might be needed for building v8 for 32-bit devices. Could you please suggest where i might be wrong?
I have used the following arguments to build v8 for arm:
target_os = “android”
is_debug = true
is_component_build = false
target_cpu = “arm”
v8_target_cpu = “arm”
v8_enable_pointer_compression = false
clang_use_chrome_plugins = false
v8_monolithic=true
v8_use_external_startup_data=false
symbol_level=2
v8_enable_i18n_support=false
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That config file looks correct to me.
Since you have debug+symbol_level, you should be able to get an accurate grasp of when things derail.
For x86, you need to set `target_cpu = “x86″` (simulator). But the arm should work straight away. Maybe you can share some stack traces.
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Hi,
I am trying to build V8 for the android x86 arch, I have followed the above-shared steps but am getting the following error while integrating with the android sample app.
[x86] SharedLibrary : libhello-jni.so
D:/workspace/v8workspace/SampleV8v8.x/app/src/main/cpp/hello-jni.cpp:42: error: undefined reference to ‘v8::platform::NewDefaultPlatform(int, v8::platform::IdleTaskSupport, v
8::platform::InProcessStackDumping, std::__ndk1::unique_ptr<v8::TracingController, std::__ndk1::default_delete >)’
../../buildtools/third_party/libc++/trunk/include/vector:1027: error: undefined reference to ‘std::__1::__vector_base_common::__throw_length_error() const’
../../src/api/api.cc:0: error: undefined reference to ‘std::__1::__vector_base_common::__throw_length_error() const’
../../buildtools/third_party/libc++/trunk/include/memory:3498: error: undefined reference to ‘std::__1::__shared_weak_count::__release_weak()’
Please help.
Regards,
Kiran
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Two potential things here:
have you tried `use_custom_libcxx=false` as config param ?
Also, NDK has a different sodlib prefix. for android, and more specifically on latest versions, I must have had to make a change in `v8/buildtools/third_party/libc++/trunk/include/__config` file:
set `_LIBCPP_CONCAT(__ndk,_LIBCPP_ABI_VERSION)`, so that stdlib’s prefix changes from __1 to __ndk1
Hope that helps.
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