Has anyone had any luck getting Allegro 5 (namely, trying for Allegro 5.2.4.0) working on a Raspberry Pi 4? I've been struggling to do so. I had to refresh myself on the procedure for getting it working on the Raspberry Pi 3. My procedure for getting it working on the Raspberry Pi 3 is as follows...

1) Image a microSD card with Raspbian Buster (latest release used, 2019-09-26).

2) Run terminal commands...

sudo apt-get update
sudo rpi-update

3) Reboot the Raspberry Pi, then run terminal commands...

wget https://github.com/liballeg/allegro5/releases/download/5.2.4.0/allegro-5.2.4.0.tar.gz
tar -zxvf allegro-5.2.4.0.tar.gz
sudo apt-get install libgdk-pixbuf2.0-dev libpango1.0-dev libcairo2-dev cmake
 libx11-dev libgl1-mesa-dev libxcursor-dev freeglut3-dev libpng-dev libjpeg-dev 
libfreetype6-dev libgtk2.0-dev libasound2-dev libpulse-dev libopenal-dev 
libflac-dev libdumb1-dev libvorbis-dev libphysfs-dev
cd allegro-5.2.4.0
mkdir build
cd build
cmake .. -DCMAKE_TOOLCHAIN_FILE=../cmake/Toolchain-raspberrypi.cmake
make
sudo make install
sudo ldconfig
cd ~

4) Create a simple example. I like using the bouncer example, saved as bouncer.c (attached).

5) Compile and run the example...

gcc bouncer.c -o bouncer $(pkg-config --cflags --libs allegro-5)
./bouncer

Works fine on the Raspberry Pi 3. On the Raspberry Pi 4 I get just a blinking cursor. I added return 0; to various locations to try and find what it seems to be getting hung-up on and it seems to be al_create_display that's hanging things up.

UPDATE:
Not sure if it'll be of any help, but I enabled allegro.log and on the RPi4 the log file stops where I have #####, whereas on the RPi3 it continues, logging 5 more lines...

opengl   D        ogl_display.c:200  _al_ogl_create_backbuffer        [   0.02937] Creating backbuffer
display  I        ogl_display.c:222  _al_ogl_create_backbuffer        [   0.02941] Deduced format ABGR_8888_LE for backbuffer.
opengl   D        ogl_display.c:231  _al_ogl_create_backbuffer        [   0.02946] Creating backbuffer bitmap
display  I        ogl_display.c:250  _al_ogl_create_backbuffer        [   0.02959] Created backbuffer bitmap (actual format: ABGR_8888_LE)
opengl   D         ogl_bitmap.c:414  ogl_upload_bitmap                [   0.03031] Created new OpenGL texture 1 (32x32, format ABGR_8888_LE)
dtor     D               dtor.c:196  _al_register_destructor          [   0.03161] added dtor for bitmap 0xd7d4c0, func 0x76e6e948
opengl   D            ogl_fbo.c:467  ogl_new_fbo                      [   0.03205] Created FBO: 1
dtor     D               dtor.c:196  _al_register_destructor          [   0.03253] added dtor for queue 0xd7e608, func 0x76e872b0

#####

dtor     D               dtor.c:227  _al_unregister_destructor        [   4.00748] removed dtor for bitmap 0xd7d4c0
opengl   D            ogl_fbo.c:423  _al_ogl_del_fbo                  [   4.00773] Deleting FBO: 1
dtor     D               dtor.c:227  _al_unregister_destructor        [   4.00788] removed dtor for timer 0xd7ad98
dtor     D               dtor.c:227  _al_unregister_destructor        [   4.05956] removed dtor for queue 0xd7e608
system   I           pisystem.c:58   pi_shutdown_system               [   4.09278] shutting down.