Missing libv8_libplatform.cr.so in Android build

[Tommaso Bossi]

Hi everyone,

I'm trying to compile V8 as a shared library for all platforms. The compilation seems to be successful, however, when I try to link it in my project I have problems with the Android versions.

Specifically, among the binaries generated for android, libv8_libplatform.cr.so is missing and consequently I get:

error: undefined reference to 'v8::platform::NewDefaultPlatform(int, v8::platform::IdleTaskSupport, v8::platform::InProcessStackDumping, std::__ndk1::unique_ptr<v8::TracingController, std::__ndk1::default_delete<v8::TracingController> >)'

when I try to build my library for Android.

Here's how I compile the linux version:

python ./tools/dev/v8gen.py x64.release -vv -- '
target_os = "linux"
is_component_build = true
v8_enable_i18n_support = false
symbol_level = 1
'
ninja -C out.gn/x64.release -t clean
ninja -C out.gn/x64.release v8

then I take all *.so files in out.gn/x64.release folder:

• libc++.so
• libchrome_zlib.so
• libv8.so
• libv8_libbase.so
• libv8_libplatform.so

Here's how I compile the Android versions (arm64 in this example):

python ./tools/dev/v8gen.py arm64.release -vv -- '
target_os = "android"
target_cpu = "arm64"
v8_target_cpu = "arm64"
is_component_build = true
v8_enable_i18n_support = false
symbol_level = 1
'
ninja -C out.gn/arm64.release -t clean
ninja -C out.gn/arm64.release v8

then I take all *.so files in out.gn/arm64.release folder:

• libc++.cr.so
• libchrome_zlib.cr.so
• libv8.cr.so
• libv8_libbase.cr.so

As you can see there is no libv8_libplatform.cr.so in this case.

However, I noticed the presence of the clang_x64_v8_arm64 folder which contains libc++.cr.so, libchrome_zlib.cr.so, libv8_libbase.cr.so, and libv8_libplatform.cr.so but no libv8.cr.so.

So now I'm not sure which are the right binaries to use.

Am I using the wrong settings? If not, why is the out.gn folder structure different for Android builds? and which binaries should I take?

Thanks a lot in advance.

PS: I'm using V8 8.3.110.9

[Tommaso Bossi]

Actually I don't think the issue is related to this specific version. I have tried with version 8.1 and I get the same result.

[Elmi Ahmadov]

I don't know your exact use case but with `symbol_level = 0`, it works for me on V8 8.3.110.9

[Tommaso Bossi]

Thanks, but it didn't work.

Anyway I managed to build the missing piece by running:

ninja -C out.gn/arm64.release v8_libplatform
ninja -C out.gn/arm64.release v8

I have not yet understood why android build behaves differently from the others, though.

[Elmi Ahmadov]

This is the complete gn args that I use to build V8 8.3.110.9 for Android:

target_os = "android"
target_cpu = "arm64"
v8_target_cpu = "arm64"

is_component_build = false
is_debug = false
use_custom_libcxx = false
v8_monolithic = true
v8_use_external_startup_data = false
v8_enable_i18n_support= false
symbol_level = 0
v8_android_log_stdout = true
v8_enable_pointer_compression = false

I build the monolithic library then use on Android, just set "v8_monolithic" to "false" if you don't want to use the monolithic library. Hope this will help