android build

[flok]

Hi,

Trying to build Embla for android.
The problem is, it keeps becoming a dynamic binary, even with the static build-flag:

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LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE := Embla
LOCAL_SRC_FILES := ../IO_perft.cpp ../Rng.cpp ../IO_EPD.cpp ../Board.cpp ../ChessPiece.cpp ../Exception.cpp ../IO.cpp ../IO_stderr.cpp ../IO_Console.cpp ../Scene.cpp ../Brain.cpp ../Debug.cpp ../Move.cpp ../Tpt.cpp ../IO_AutoPlay.cpp ../IO_UCI.cpp ../MoveSort.cpp ../Semaphore.cpp ../config.cpp ../ALG_position.cpp ../MoveList.cpp ../error.cpp ../db.cpp ../Utils.cpp ../Book.cpp ../DBBook.cpp ../DBBookWDL.cpp ../DBBookEval.cpp ../History.cpp ../PV.cpp ../BookPolyglot.cpp ../DetectBookFile.cpp ../DBBookEvalSqlite3.cpp ../DBBookLearn.cpp ../Tune.cpp ../IO_Xboard.cpp ../Ptt.cpp ../Main.cpp

LOCAL_CPPFLAGS := -std=gnu++14 -Wall -fPIE -DVERSION=\"2.0.7\" -DNAME_EXTRA=\"\" -fexceptions
LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -fPIE -pie -static

LOCAL_LDFLAGS := -static

include $(BUILD_EXECUTABLE)

Results in:

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folkert@belle:~/Projects … .9.1_2205/branches/Android/jni Android(1) 6s ‡ file ../libs/armeabi/Embla
../libs/armeabi/Embla: ELF 32-bit LSB shared object, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /usr/lib/libc.so.1, BuildID[sha1]=1292a6bce7808ecddf110f5aa7a43d154248f472, stripped

Any ideas?

[flok]

Any ideas?

Yes: remove the position-independent-code-flag.
Then the resulting binary is static and can be used in Aart's chess board program!
https://vanheusden.com/Embla/files/android-2.0.7.zip

[Ras]

The problem is, it keeps becoming a dynamic binary, even with the static build-flag:

That's a good thing because executables with position independent code are technically libraries that happen to have a main(). Here's what my Engine looks like:

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$ file CT800_V1.34_64
CT800_V1.34_64: ELF 64-bit LSB shared object, ARM aarch64, version 1 (SYSV), dynamically linked, interpreter /system/bin/linker64, stripped

$ file CT800_V1.34_32
CT800_V1.34_32: ELF 32-bit LSB shared object, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /system/bin/linker, stripped

You shouldn't link statically for 3 reasons:

1) It increases up the file size both for storage and runtime.
2) Bugfixes for the standard library will not reach static binaries.
3) You cannot have position independent code in a static binary.

Position independent code is required under Android 5.0 (from 2014) or later. Unless you are using Android older than 5.0, the static executable should not run. However, the oldest Android that supports PIE is 4.1 (from 2012), so Android 4.0 or older cannot run position independent code.

[flok]

Position independent code is required under Android 5.0 (from 2014) or later. Unless you are using Android older than 5.0, the static executable should not run.

Hmmm, it runs fine on my samsung galaxy s9 with android 9.

[Ras]

Hmmm, it runs fine on my samsung galaxy s9 with android 9.

Actually, also my Nokia 6 with Android 9 runs the static engines which look like this (PIE removed in build script, static added):

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$ file CT800_V1.34_S64
CT800_V1.34_S64: ELF 64-bit LSB executable, ARM aarch64, version 1 (SYSV), statically linked, stripped

$ file CT800_V1.34_S32
CT800_V1.34_S32: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), statically linked, stripped

That's strange because some years ago, Android wouldn't run them.

[pedrox]

I've recently moved from sourcery codebench to NDK. The main problem I had with codebench sourcery is that it is no longer free and I do not know if it is being continued. On the other hand, the executable I did does not work on android 8 on a tablet huwai mediapad t5. With codebench sourcery I always created statical binaries, they worked on android version 4 but I also tried it in version 5 and 7.

To compile with make I created a bat file:

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@echo off

rem currently, Android NDK r19c has been used with the standalone toolchain generated with:
rem make_standalone_toolchain.py --arch arm64 --api 21 --install-dir d:\android-standalone-64
rem the script make_standalone_toolchain.py is in the NDK under: build\tools

set "make_path_64=D:\android-standalone-64\bin"
set "make_64=%make_path_64%\make"
set "OLD_PATH=%PATH%"
set "PATH=%make_path_64%;%OLD_PATH%"

echo Generating DanaSah 64 bit for ARM-Android.

cmd /c "%make_64%"

pause

My Makefile file:

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CC = clang
CFLAGS = -m64 -march=armv8-a -DUNDER_ARM -DUNDER_64BIT -fPIE -Wall -Wextra -Werror -O2 -std=c99 -fno-strict-aliasing -fno-strict-overflow -ffunction-sections -fdata-sections
LIBS = -static -ldl -lm -s ./gtb/ARM/64/libgtb.a

.SUFFIXES: .c .o
 
OBJS = aleatorio.o atacado.o busqueda.o configura.o consola.o danasah.o \
     egbb.o egtb.o entradas.o evalua.o fen.o hash.o libro.o movimientos.o \
	 multipv.o salidas.o see.o test.o uci.o variables.o xboard.o
	 
all: danasah

.c.o: 
	$(CC) $(CFLAGS) -c $< -o $@

danasah: $(OBJS) 
	$(CC) -o danasah $(OBJS) $(CFLAGS) $(LIBS)

clean:
	del *.o
	del danasah

I have continued creating a static binary, the executable created I tested it works well on android 7 and android 8.

[Ras]

To compile with make I created a bat file:

That looks quite familiar to me. However, with NDK r19, building the standalone chains via the Python script is not necessary anymore. For now, this still works, but that will be removed in r20, see the changelog https://github.com/android-ndk/ndk/wiki/Changelog-r19 .

The guide has been updated, see here: https://developer.android.com/ndk/guide ... ld_systems . Basically, you just call Clang directly as delivered in the NDK download and hand over the -target flag, I have tried that, and it works.

Here's my batch file modified for NDK r19 or later, stripped down to ARM-Android 64 bit as target. Note that I have been using the 32 bit Windows download of the NDK - the path is a little different for the 64 bit download, see below.

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@echo off

rem currently, Android NDK r19c (32 bit Windows version) has been used.
rem replace the "windows" with whatever host system you are using:
rem Windows 32 bit: windows
rem Windows 64 bit: windows-x86_64
rem Linux 64 bit:   linux-x86_64
rem macOS 64 bit:   darwin-x86_64
set "compiler_path=C:\android-ndk-r19c\toolchains\llvm\prebuilt\windows\bin"

set "fw_ver=V1.34"
set "compiler=%compiler_path%\clang"

rem target options
set "arm64opt=-target aarch64-linux-android21"

rem get the current directory
set "starting_dir=%CD%"

rem changes the current directory to the directory where this batch file is.
rem not necessary when starting via the Windows explorer, but from IDEs or so.
cd "%~dp0"

rem it is not necessary to add the compiler paths to PATH, but it looks more
rem future proof to have that.
set "OLD_PATH=%PATH%"
set "PATH=%compiler_path%;%OLD_PATH%"

rem *** the source files are fetched relative to the path of this batch file

echo Generating CT800 64 bit for ARM-Android.
set "compiler_options=-DTARGET_BUILD=64 -m64 -march=armv8-a -pie -fPIE -Wl,-pie -Wall -Wextra -Wstrict-prototypes -Werror -O2 -std=c99 -fno-strict-aliasing -fno-strict-overflow -ffunction-sections -fdata-sections -Wl,--gc-sections -Wl,-s"
cmd /c "%compiler%" %arm64opt% %compiler_options% -o output\CT800_%fw_ver%_andarm64 play.c kpk.c eval.c move_gen.c hashtables.c search.c util.c book.c

set "PATH=%OLD_PATH%"

rem go back to the starting directory
cd "%starting_dir%"

pause

The resulting engine info, same as from NDK r18:

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$ file CT800_V1.34_64
CT800_V1.34_64: ELF 64-bit LSB shared object, ARM aarch64, version 1 (SYSV), dynamically linked, interpreter /system/bin/linker64, stripped