Question

What is wrong with my make file?

Android.mk

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE    := foo
LOCAL_SRC_FILES := foo.c
LOCAL_EXPORT_LDLIBS := -llog
include $(BUILD_SHARED_LIBRARY)

foo.c

#include <string.h>
#include <jni.h>
#include <android/log.h>

#define  LOG_TAG    "foo"
#define  LOGI(...)  __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)

void test() {
    LOGI("test");
}

ndk-build

foo.c:9: undefined reference to `__android_log_print'

Modify line LOCAL_EXPORT_LDLIBS := -llog to LOCAL_LDLIBS := -llog — Shiv Buyya, Mar 11, 2021 at 6:57

Kyle · Answer 1 · 2011-01-31 05:46:33Z

102

You need to add

LOCAL_LDLIBS := -llog

to Android.mk

answered Jan 31, 2011 at 5:46

Kyle

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1

correct. if there are multiple libraries, need to add this statement for each one of them (after CLEAR VARS)
– user13107
Jan 19, 2016 at 4:17

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Tim Cooper · Accepted Answer · 2013-06-04 12:57:25Z

92

Try the following in your Android.mk file:

LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog

edited Jun 4, 2013 at 12:57

Tim Cooper

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answered Dec 15, 2010 at 23:29

Ryan Reeves

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1

What is the necessary to add this? Would you Please explain in detail?
– Dhasneem
Mar 7, 2013 at 12:40
its adding an android library to the make file - and it worked for me too
– gheese
Apr 24, 2013 at 15:08
9

the -L is unnecessary. Please accept the other answer instead.
– Jeff Allen
Jun 21, 2013 at 11:23
5

If using the new Gradle NDK integration in Android Studio 1.3, you need to add ldLibs = ["android", "log"] to your android.ndk options
– Stephen Kaiser
Sep 24, 2015 at 4:20
1

What if we are not using Android.mk's ?
– cagdas
Oct 27, 2016 at 12:17

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BoredT · Answer 3 · 2014-12-10 17:41:47Z

86

If you use Android Studio and gradle, it ignores Android.mk. Add this to your build.gradle file:

android {
    defaultConfig {
        ndk {
            moduleName "your_module_name"
            ldLibs "log"
        }
    }
}

edited Dec 10, 2014 at 17:41

answered Dec 4, 2014 at 14:58

BoredT

1,5901515 silver badges1919 bronze badges

7

I wonder where this is documented. I was looking for this as well.
– Randy Sugianto 'Yuku'
Dec 19, 2014 at 6:19
1

I was getting "undefined reference to '__android_log_print'" before I have added ldLibs. Thanks.
– Support Ukraine
Jan 2, 2015 at 10:54
2

Adding this fixed it for me. Just make sure to add the ndk part in the build.gradle inside the app folder instead of the one in the project folder (module name).
– mathiass
Jun 6, 2015 at 20:59
As of Gradle 2.5 use 'ldLibs += "log"' slight syntax change
– Lorne K
Oct 3, 2015 at 0:00
15

this did NOT work for me. this is what I had to do: ldLibs.addAll(["android", "log"])
– ᴛʜᴇᴘᴀᴛᴇʟ
Feb 4, 2016 at 7:09

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lewkka · Answer 4 · 2016-11-09 17:22:08Z

For Android Studio 2.2 and tools.build:gradle:2.2.0 using CMake add or edit row in CMakeLists.txt:

target_link_libraries(<your_library_name> 
                      android 
                      log)

Thats connecting log library to yours.

DroidlikeCode · Answer 5 · 2016-05-05 16:49:13Z

If you upgrade to Android Studio 2.1, above answers do not work, need use ldLibs.add() to load the lib as below:

android.ndk {
    moduleName = "[the_module_name]"
    ldLibs.addAll(['android', 'log'])
}

best modern (late 2017) answer
– EdgarArout
Sep 2, 2017 at 0:37 — EdgarArout, Sep 2, 2017 at 0:37

DNax · Answer 6 · 2017-12-14 00:05:30Z

In case the project you are working on has the following characteristics that differ from other 'standard' answers:

Not using Android Studio
Not using gradle and the integrated CMake
No Android.mk or Application.mk used at all for build
Using CMake and the toolchain directly (maybe your project is Qt based and without using QtCreator neither)

The following target_link_libraries usage makes it:

    find_library(ANDROID_LOG_LIB log)
    target_link_libraries(${TARGET_NAME} ${ANDROID_LOG_LIB})

Being TARGET_NAMEthe name of the target to build (having set it up before with add_library or add_executable).

find_library is equally important as well as setting up the toolchain properly (use the toolchain provided by Android SDK at ANDROID_SDK_HOME/cmake/<version>/android.toolchain.cmake so it sets up CMAKE_SYSROOTwhich is used by find_ commands).

Only solution that helped me! Thanks a ton, I would extend it by a test if the library was found for better feedback to the developer as here stackoverflow.com/a/37868829/10030695 — ManuelTS, Jan 6, 2019 at 15:02

Sandeep · Answer 7 · 2014-10-09 06:16:23Z

We can link a shared library in Android in 3 ways. In below 3 cases, the lines mentioned should be added in Android.mk

So here are the three ways.

1. LOCAL_LDLIBS way
LOCAL_LDLIBS := -llog

For some reason if 1 doesnt work(it did not work for me), You can try below 2 ways

2. LOCAL_LDFLAGS way
LOCAL_LDFLAGS := -llog

3. LOCAL_SHARED_LIBRARIES way
LOCAL_SHARED_LIBRARIES += liblog

Of course you also need to include #include <android/log.h> in your C/H file.

SudoSURoot · Answer 8 · 2014-09-05 21:17:15Z

Yes, you do need to add: LOCAL_LDLIBS := -llog as the other answers/comments have specified, however the original question did not specify if he use the jni library as: LOCAL_JNI_SHARED_LIBRARIES or as LOCAL_REQUIRED_MODULES.

I can pretty much say for sure that he has it used it as: LOCAL_REQUIRED_MODULES because of the LOCAL_EXPORT_LDLIBS := -llog in the question... unless that was added after an edit.

If you use LOCAL_REQUIRED_MODULES the shared library is installed in /system/lib instead of into the apk, because it is a required module. Therefore you will need to add LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog instead of just LOCAL_LDLIBS := -llog so that when the build system is building & linking the jni shared library, it will have the -llog definitions in the correct place, available to be built under $OUT/root/system/lib. Otherwise you will continue to get the same answer, even if you only add LOCAL_LDLIBS := -llog.

So, those who commented that the -L is not needed, and the other answer was correct, they were actually incorrect in this situation.

Thank you for actually explaining what's going on!
– Richard
Jul 27, 2015 at 4:47 — Richard, Jul 27, 2015 at 4:47

sethbabs · Answer 9 · 2015-11-27 01:40:00Z

In lieu with

If using the new Gradle NDK integration in Android Studio 1.3, you need to add ldLibs = ["android", "log"] to your android.ndk options – Stephen Kaiser Sep 24 at 4:20

use ldLibs.addAll(["android", "log"]) for the experimental plugin

user3535040 · Answer 10 · 2014-04-15 08:24:14Z

Add

LOCAL_SHARED_LIBRARIES:= \
        libbinder                       \
        liblog                          \

to Android.mk

Why? Please explain why this answer should work for the asker. — L0j1k, Apr 15, 2014 at 9:14

James · Answer 11 · 2020-03-17 09:47:08Z

2

-DCMAKE_CXX_FLAGS="-llog" helps me

answered Mar 17, 2020 at 9:47

James

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NickUnuchek · Answer 12 · 2015-08-07 12:12:48Z

This helped for me:

Android.mk

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

LOCAL_MODULE    := nativeDemo
LOCAL_SRC_FILES := main.cpp
LOCAL_LDLIBS += -llog

include $(BUILD_SHARED_LIBRARY)

Praveen Kumar KR · Answer 13 · 2017-09-28 04:21:55Z

In the android studio version 2.2 and higher, there is inbuilt support for CPP when you create a new project. Also, the liblog.so is included by default. Nothing to be done apart from including the header file (android/log.h).

Checkout app/CMakeLists.txt that is created by the studio when we create new android studio project. We can see that the find_library() block and target_link_libraries() block for loglib are already present.

Also, pay attention towards the function syntax. It should be:

__android_log_print (int priority, const char *tag, const char *fmt,...);

In my case, I had left out tag parameter and ended up spending good 3 days in figuring it out.

More about CMake: Add C and C++ Code to Your Project

jizhihaoSAMA · Answer 14 · 2020-07-03 07:19:36Z

add LOCAL_SHARED_LIBRARIES:= liblog to Android.mk can solve my isuue. This is because the __android_log_print is defined in libLog

score 0 · Answer 15

TO build with Android.bp, follow the below solution:

In this -android_log_print is defined in NDK, so for this, there is already a library is available. Use "liblog" library using shared_libs tag, take reference of the below code:

target: {
        android: {
            cppflags: [
                "-g",
                "-DUSE_LIBLOG",
            ],
            shared_libs: ["liblog"], // can use other dependency if required.
        },
        darwin: {
            enabled: false,
        },
    },

秋天的原野

夜静海涛三万里，月明飞锡下天风。

opencv交叉编译：undefined reference to `__android_log_print'

undefined reference to `__android_log_print'

15 Answers

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