Android builds

[bbbradsmith]

Try running RetroArch on Android. See what's involved. Theoretically it should be able to build for these platforms.

The libretro/hatari CI build should probably help understand how to compile: https://git.libretro.com/libretro/hatari/-/pipelines

[DJM75]

Any progress on this? Would love to see it included in RetroArch for Android.

[bbbradsmith]

No work has been done on this, no.

[DJM75]

Ok I tried to compile it for Android but this core, unlike most libretro cores (including also the old Hatari core), doesn't use a JNI folder with an Android.mk file so I can't compile it with ndk-build (which would make things a lot easier).

So I tried a manual build with "cmake" (using the "CMakeLists.txt" file in the "hatari" directory). No luck. Then I also tried to add my CFLAGS in the "makefile" and run a "make". No matter what, I always get the following error:

/usr/bin/ld: hatari/build/src/libcore.a: error adding symbols: file in wrong format
collect2: error: ld returned 1 exit status
make: *** [makefile:124: build/hatarib.so] Error 1

Any help?

[bbbradsmith]

Are you deleting and rewriting this message over and over? Could you please just edit it instead? I just received 9 e-mail notifications.

[DJM75]

Lol sorry about that man, edit didn't work on my phone, now I am on PC.

[bbbradsmith]

I don't have any ideas based on the error message you posted. In general each new compiler requires some sort of subtle tweaks to make compatible. At the moment I'm not able to try and set up an android build for this myself, so I can't really follow along directly.

[DJM75]

I don't have any ideas based on the error message you posted. In general each new compiler requires some sort of subtle tweaks to make compatible.

Are the required static libraries ZLIB and SDL2 linked directly to the target program? I ask this because I am using a Linux machine (Ubuntu) to cross compile for Android (arm64). I searched around for my error ("error adding symbols: file in wrong format", "Relocations in generic ELF (EM: 183)") and that seems to happen when you are trying to link object files or libraries that were compiled for a different architecture or operating system. So maybe the static libraries ZLIB and SDL2 would need to be compiled too for arm64? ...

[bbbradsmith]

make full is written to compile both ZLIB and SDL2, it does not use pre-existing libraries, so they should be built with the same compiler and settings as everything else.

You might look at the build scripts for RPi for an example of how this was done for a cross compiler. You might need to do something similar:

hatariB/.github/workflows/build.yml

Line 195 in 8cd70b6

build-rpi64:

[DJM75]

A bit of progress, I was able to compile it with no errors but I had to fix a line in "floppy.c" because of this error:

/home/djmarco/hatariB/hatari/src/floppy.c:790:7: error: use of undeclared identifier 'core_prevent_eject_save'
        if (!core_prevent_eject_save)

But now the problem is that the core crashes in RetroArch. I enabled log and I have this error:

Error(s): dllopen failed: cannot locate symbol "pSdlGuiScrn" referenced by "/data/user/0/com.retroarch.aarch64/cores/hatarib.so"

We are almost getting there... ;)

[Uukrull]

Did you compile it with -D__LIBRETRO__? The errors you are having seems related to that. For example, core_prevent_eject_save is defined here:

#ifdef __LIBRETRO__
extern bool core_savestate_floppy_modify;
static bool core_prevent_eject_save = false;
#endif

[DJM75]

Did you compile it with -D__LIBRETRO__?

Yes, for some reasons the Android NDK toolchain (Clang, Android doesn't use GCC) didn't want to append any of those compile CFLAGS set in the makefile... Now I fixed that and everything compiles perfectly. But when I try to open the core in RetroArch now there's a new error (and this time I really have no clue what it is... and searching online didn't help):

Error(s): dllopen failed: cannot locate symbol "Android_JNI_FileSize" referenced by "/data/user/0/com.retroarch.aarch64/cores/hatarib.so"

[DJM75]

Ok here we go, it was a nightmare trying to understand all the runtime errors that RetroArch gave every time but finally here are the builds for Android. The builds are based on the latest available source (v0.3 unstable) and in the archive there are both 64-bit and 32-bit versions.

NOTE: For all those who would like to try the core, a little suggestion... Since on the latest Android versions it's really complicated to access the internal "data" folder where RetroArch stores the cores and the info files, I suggest you to rename the "hatarib.so" file to "hatari_libretro.so" so as to be recognized by RetroArch as the "old" Hatari core (in this way there is no need to copy the .info file, just update the info files from RetroArch's Online Updater and then install the core manually). All this while waiting for hatariB to become an official core in RetroArch ;)

Awesome work Brad, this core is really a big step forward compared to the old Hatari 1.8.0 core!

Download:
hatarib-android--2023-12-20-082452--8cd70b6.zip

[bbbradsmith]

Can you document the build steps that were required? The goal is to automate it and add to the CI builds like the other platforms.

[DJM75]

Yes of course.

The real problem with the Android build was understanding how to get to an error-free build by reducing the necessary parameters to the minimum. I had to do hundreds of attempts, it was enough to just set one parameter more (or less) than those required and the build, even if completed without errors, then gave runtime errors in RetroArch. It was a try and try again, Android is a mess and sometimes you also need to try different NDK versions to find the right one for that particular building...

Ok, first of all I made the building on a clean and updated Ubuntu machine (sudo apt update --> sudo apt -y full-upgrade) installing the following packages:

• Make --> sudo apt install make

• CMake (v3.28.3, older versions gave me building errors) --> sudo snap install cmake

• Clang (even if Clang in the NDK toolchain will be used for the building, to compile some files it is also required to install Clang on the machine) --> sudo apt install clang

• UnZip --> sudo apt install unzip

After preparing the environment, the first thing to do is to download the Android NDK (here is the link to the latest version https://dl.google.com/android/repository/android-ndk-r26c-linux.zip ) and unzip it into a folder.

Then I had to modify makefile.sdl and set the CFLAGS --enable-joystick=yes and --enable-haptic=yes (Android SDL requires this or the building will give errors).

And finally here is the script that I wrote with all the steps for a clean building (obviously the paths relating to the NDK needs be modified based on the path where it was installed):

#!/usr/bin/bash

###### ARM64-V8A ######
rm -rf build hatari/build SDL zlib zlib_build
export CC=/home/djmarco/android-ndk-r26c/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android26-clang

### SDL BUILD ###
# Don't foget to set "--enable-joystick=yes" and "--enable-haptic=yes" in makefile.sdl
export CONFIGURE_FLAGS="--host=aarch64-linux-android"
make -f makefile.sdl

### ZLIB BUILD ###
make -f makefile.zlib

### HATARIB BUILD ###
export CMAKEFLAGS="-DCMAKE_ANDROID_ARCH_ABI=arm64-v8a -DCMAKE_ANDROID_NDK=/home/djmarco/android-ndk-r26c -DCMAKE_BUILD_TYPE=Release -DCMAKE_SYSTEM_NAME=Android -DCMAKE_SYSTEM_VERSION=26"
make WERROR=-Wall

To build for Android 32-bit (armeabi-v7a) the script is exactly the same, just 3 lines need to be modified:

export CC=/home/djmarco/android-ndk-r26c/toolchains/llvm/prebuilt/linux-x86_64/bin/armv7a-linux-androideabi26-clang

export CONFIGURE_FLAGS="--host=armv7a-linux-androideabi"

export CMAKEFLAGS="-DCMAKE_ANDROID_ARCH_ABI=armeabi-v7a -DCMAKE_ANDROID_NDK=/home/djmarco/android-ndk-r26c -DCMAKE_BUILD_TYPE=Release -DCMAKE_SYSTEM_NAME=Android -DCMAKE_SYSTEM_VERSION=26"

That's all, hope this helped! ;)