Cross-compiling ScummVM on for Raspberry Pi
Installing the official Raspberry Pi cross-compiler on PC
We will clone the Raspberry Pi tools repository which includes the cross-compiler we need:
git clone https://github.com/raspberrypi/tools.git
It will get cloned to a directory called tools at your current location.
Add it to the PATH environment variable so that we have the cross-compiler binaries available from our scummvm building directory. For example, if my Raspberry Pi tools repository ended cloned in tools under my home directory, I would do:
After adding the cross-compiler executables directory to PATH, we should be able to run arm-linux-gnueabihf-gcc, arm-linux-gnueabihf-g++, etc... just try. They should yield an error because you pass them no input files, but that's expected. It's just a test so we know we have the cross-compiler installed and accessible.
Installing the needed Raspberry Pi headers and libraries on PC
We need to copy over the /usr, /lib and /opt directories from your Raspbian SD Card to your host PC (the computer were you will do the cross-compilation) for the needed headers and libraries to be available.
Of course, first you'll have to install any additional libraries from Raspbian running on the Pi before expecting them to be available so, if you want compile ScummVM with FLAC support, you should have installed the libflac development libraries on the Pi beforehand.
As an example, on the Raspberry Pi running Raspbian (Buster) OS 3.2 (January 2020) we can execute the following to install third party libraries that ScummVM features and game engines need:
sudo apt-get update sudo apt-get upgrade sudo apt-get install -y --no-install-recommends \ libsdl2-dev \ liba52-0.7.4-dev \ libjpeg62-turbo-dev \ libmpeg2-4-dev \ libogg-dev \ libvorbis-dev \ libflac-dev \ libmad0-dev \ libpng-dev \ libtheora-dev \ libfaad-dev \ libfluidsynth-dev \ libfreetype6-dev \ libcurl4-openssl-dev \ libsdl2-net-dev \ libspeechd-dev \ zlib1g-dev
On the host PC we first export the path where we will copy these into, and then we manually copy them. I choose to copy the Raspberry Pi headers and libraries to /opt/rpi_root, but any other path with the right permissions for your user (within common sense) should be ok:
mkdir -p /opt/rpi_root export RPI_ROOT=/opt/rpi_root cd <SD_mountpoint_directory> cp -R usr lib opt $RPI_ROOT
Now we configure scummvm buildsystem so it knows what backend we want and where is our raspberry pi local sysroot living, containing the Raspberry Pi headers and libs the cross-compiler and linker will need. In this example configuration, we disable additional libs, and debug symbols since it's intended for final users.
./configure --host=raspberrypi --with-sdl-prefix=$RPI_ROOT/usr --disable-debug --enable-release --enable-optimizations --disable-mt32emu --disable-flac --disable-mad --disable-vorbis --disable-tremor --disable-fluidsynth --disable-taskbar --disable-timidity --disable-alsa
Remember you should have exported the RPI_ROOT enviroment variable previously. On the raspberrypi host, SDL2 will be always used since it provides graphics acceleration.
Note: If you are building ScummVM on your RPi itself, you might run out of memory during linking. If you use GNU ld for compiling you can try exporting LDFLAGS="-Wl,--no-keep-memory" before running configure. This tells GNU ld to optimize for memory usage.
Run the following commands:
make clean make -j$(nproc)
Installing ScummVM on the Raspberry Pi
Simply copy over the resulting scummvm executable to your Raspberry Pi (Raspbian OS) SD Card. A good idea is to create a scummvm folder in your /home/pi directory on the Raspian OS SD Card, and put the executable there along with any games you want to use with it.