V8 for Android undefined symbol v8::base::SysInfo::NumberOfProcessors()

[ibon tolosana]

Hi,

after successfully cross-compiling v8 for raspberry I am getting a linker error on both ubuntu16.04 and and CentOS 7.2.

I am getting this:

  CXX(host) /data/build/v8/out/android_arm.release/obj.host/mksnapshot/src/snapshot/mksnapshot.o

  LINK(host) /data/build/v8/out/android_arm.release/mksnapshot

/data/build/v8/out/android_arm.release/obj.host/src/libv8_libplatform.a(/data/build/v8/out/android_arm.release/obj.host/v8_libplatform/src/libplatform/default-platform.o):../src/libplatform/default-platform.cc:function v8::platform::CreateDefaultPlatform(int): error: undefined reference to 'v8::base::SysInfo::NumberOfProcessors()'

/data/build/v8/out/android_arm.release/obj.host/src/libv8_libplatform.a(/data/build/v8/out/android_arm.release/obj.host/v8_libplatform/src/libplatform/default-platform.o):../src/libplatform/default-platform.cc:function v8::platform::DefaultPlatform::SetThreadPoolSize(int): error: undefined reference to 'v8::base::SysInfo::NumberOfProcessors()'

I have checked /v8/out/android_arm.release/obj.host/v8_libbase/src/base/sys-info.o and NumberOfProcessors function is there. 

I have extracted sys-info.o from libv8_libbase.a and made sure NumberOfProcessors is referenced there, but the linker get undefined reference.

Since the snapshot is not important to me, I have tried to link with libv8_base.a libv8_libbase.a libv8_libplatform libv8_libsampler.a  and libv8_nosnapshot.a (instead of external snapshot) but i get the same undefined referenced symbol.

any ideas ? 

help please ^^

thanks.

- i

[Rodolph Perfetta]

Hi,

I am not sure I follow what you are doing: if your cross compilation was successful why do you need to build and link mksnapshot again? Secondly cross compiling for raspberry will target arm linux, but the lines you posted reference android_arm. Did you intend to mix both target?

Rodolph

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[ibon tolosana]

Hi Rodolph, sorry, I did not explain myself properly.

I compiled for pi successfully. As a different compilation. Nothing to do with this.

Now i try to compile v8 for android.

And i get that missing symbol.

Sorry for the misunderstanding.

thanks.

[Rodolph Perfetta]

I see. I don't have experience with Android builds but have you checked the wiki: https://github.com/v8/v8/wiki/D8%20on%20Android

Rodolph

[ibon tolosana]

Hi Rodolph,

yes, I did follow that instructions.

What surprises me most is that v8::base::SysInfo::NumberOfProcessors exists on the libv8_libplatform.a, but the linker seems to pass on it.

I fixed by defining the symbol myself though.

Thanks.

- ibon

[ibon tolosana]

Fixed.

So it turns out it was a matter of the order of the libs handed to the linker.

Assuming after compilation different libs are created for base, platform, etc, the correct order in the .mk should be:

1. base
• (external_snapshot, snapshot) or (nosnapshot) depending on your needs
2. libplatform
3. libbase
4. libsampler
   

With this, all linker symbols are found correctly:

LOCAL_STATIC_LIBRARIES := v8_base v8_nosnapshot v8_libplatform v8_libbase v8_libsampler

Thanks.

[Dzung Tran]

Can you tell me where can I find this LOCAL_STATIC_LIBRARIES in v8 directory to modify?

I am getting the same error. I am surprise this is not fix in the v8 repo.

[ibon tolosana]

Hi,

I fixed the problem by reordering the link libraries list. I used the following as the source for external libs (android.mk)

LOCAL_STATIC_LIBRARIES := v8_base v8_libplatform v8_libbase v8_libsampler v8_snapshot 

hope that helps.

- i