undefined reference to '__android_log_print'

Question

I have compiled and ran Android 8 on emulator. I want to view the behavior of ART when installing and opening an application in AOSP. I added this line to dex2aot.cc file:

#include <android/log.h>
#define LOGI(...) ((void)__android_log_print(ANDROID_LOG_INFO, "native-lib", __VA_ARGS__))
#define LOG_TAG "foo"

and this one LOGI("DOOOOOOOOTOOOOOOOOOOOOOOOO");

~Dex2Oat() {
// Log completion time before deleting the runtime_, because this accesses
// the runtime.

LOGI("DOOOOOOOOTOOOOOOOOOOOOOOOO");

LogCompletionTime();

I also created android.mk in the dex2aot folder containing this:

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_SHARED_LIBRARIES:= liblog

Then I run these commands

source build/envsetup.sh
lunch aosp_arm-eng
make -j8

And I get undefined reference error. I looked up the error, but most solutions are very old. Is there any new solution? Should I modify android.mk in the build folder? I appreciate your help.

Regards,

Answer 1

I also created android.mk in the dex2oat folder

This does not work. The pattern for declaring a module in an Android.mk would be, e.g. for creating a binary:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
...
LOCAL_MODULE := name_of_your_module
include $(BUILD_EXECUTABLE)

This defines a new module name_of_your_module, which is of type executable. You could then fill in details about the module in place of the ..., for example you could add source files with LOCAL_SRC_FILES := ... or link against shared libraries with LOCAL_SHARED_LIBRARIES := ....

In the code you posted, you gave the LOCAL_SHARED_LIBRARIES declaration, but I do not see a module declaration surrounding it. So the build system has no way of knowing what module wants to link against liblog. So when you would want to declare a new module linking against liblog, you would have to make sure that your LOCAL_SHARED_LIBRARIES is in between a include $(CLEAR_VARS) and a LOCAL_MODULE := ... / include $(BUILD_EXECUTABLE) (or an other module type, in case you want to build a static or shared library).

However, this only applies when you want to create a new module. From what I understand, you do not actually want to create a new module, but add a linker dependency to an existing module, namely dex2oat. To achieve this, you would have to modify the existing module declaration of dex2oat. Now you said you are using Android 8, where this module is in declared in ./art/dex2oat/Android.bp. Creating a new Android.mk for an existing module declared in a Android.bp will not work. Instead you have to modify the Android.bp.

In ./art/dex2oat/Android.bp, find the module declaration of dex2oat:

art_cc_binary {
    name: "dex2oat",
    defaults: [
        "dex2oat-defaults",
    ],
    shared_libs: [
        "libart",
        "libart-compiler",
        "libbase",
        "libsigchain",
    ],
}

In the shared_libs list, add the library you want to link against, so in your case, "liblog".