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Editorial Team
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Asked: 2026-06-05T17:37:07+00:00

I’m having a problem that only seems to happen on my Lenovo Thinkpad Tablet

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I’m having a problem that only seems to happen on my Lenovo Thinkpad Tablet running Android OS 3.1. I am running a native app using the NDK. The application runs fine in the emulator and on other devices.

Whenever I allocate an int64_t (defined as long long) I get a SIGILL crash with signal (4). As an example these lines will crash on the device.

int64_t i = 0; 
long long j = 0;

I should note, the application runs fine, I can see menus rendering correctly, animating and waiting for input. When I touch, I allocate int64 variables for the timestamps, this is when the crash occurs. Regardless of where I allocate an int64 in this app, I get a crash.

The strange thing is, I loaded up the native-activity sample that comes with the NDK and tried allocating the above data types and it works fine. Both applications have the same Application.mk and very similar Android.mk files. I have also tried cleaning the project.

I am really unsure of what to look at next.

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1 Answer

  1. Editorial Team

    I have solved the problem. This project is a port from an iOS project which has some NEON math classes in it. We use the following flags for NEON support:

     -mfpu=neon -mfloat-abi=softfp

    We used the same flags in the Android project initially which worked initially. Although as soon as we got a new test device (Lenovo Thinkpad Tablet) we started getting the crash as above. Since building for armeabi-v5 worked and doesn’t use NEON I knew it was related. It turns out there are better ways to compile for NEON for Android than using the above flags. I removed the above flags so that our Android.mk looks like so:

    ifeq ($(TARGET_ARCH_ABI),armeabi-v7a)
     LOCAL_CFLAGS   += -DHAS_NEON=1
     MY_SRC_FILES   += myfile.cpp.neon
else
     LOCAL_CFLAGS   += -DHAS_NEON=0
     MY_SRC_FILES   += myfile.cpp
endif

    This means that only the files that actually need to be built for NEON are. The processor inside the Lenovo Thinkpad Tablet (Nvidia Tegra 2) doesn’t support NEON so clearly building all files with NEON support was generating the instructions in a way which the processor didn’t like.

    Thanks for Keith for suggesting that I try the other architectures which led me to my solution.

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