Errors linking a GNU/Linux version

[vanfanel]

Hi there, @EXL

I have just discovered this Gish SDL2 port you have done, which I believe is the only SDL2 version available of the sources (correct me if I am wrong on this).

I have tried to build a GNU/Linux version (not Android, but plain GNU/Linux) using gish/src/main/cpp/CMakeLists.txt, and the game builds, but it fails during the final linking phase:

[ 98%] Linking C executable Gish
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/custom.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/custom.c.o:(.bss+0x8): multiple definition of `fwrite2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x8): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/game.c.o:(.bss+0x0): multiple definition of `numofobjectrenders'; CMakeFiles/Gish.dir/Gish/game/editor.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/game.c.o:(.bss+0x20): multiple definition of `objectrender'; CMakeFiles/Gish.dir/Gish/game/editor.c.o:(.bss+0x20): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/gametexture.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/gametexture.c.o:(.bss+0x8): multiple definition of `fwrite2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x8): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/high.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/high.c.o:(.bss+0x8): multiple definition of `fwrite2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x8): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/level.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/level.c.o:(.bss+0x8): multiple definition of `fwrite2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x8): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/lighting.c.o:(.bss+0x0): multiple definition of `numofobjectrenders'; CMakeFiles/Gish.dir/Gish/game/editor.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/lighting.c.o:(.bss+0x20): multiple definition of `objectrender'; CMakeFiles/Gish.dir/Gish/game/editor.c.o:(.bss+0x20): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/music.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/music.c.o:(.bss+0x8): multiple definition of `fwrite2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x8): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/player.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/player.c.o:(.bss+0x8): multiple definition of `fwrite2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x8): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/prerender.c.o:(.bss+0x0): multiple definition of `numofobjectrenders'; CMakeFiles/Gish.dir/Gish/game/editor.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/prerender.c.o:(.bss+0x20): multiple definition of `objectrender'; CMakeFiles/Gish.dir/Gish/game/editor.c.o:(.bss+0x20): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/render.c.o:(.bss+0x0): multiple definition of `numofobjectrenders'; CMakeFiles/Gish.dir/Gish/game/editor.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/render.c.o:(.bss+0x20): multiple definition of `objectrender'; CMakeFiles/Gish.dir/Gish/game/editor.c.o:(.bss+0x20): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/replay.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/game/replay.c.o:(.bss+0x8): multiple definition of `fwrite2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x8): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/sdl/endian.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/sdl/endian.c.o:(.bss+0x8): multiple definition of `fwrite2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x8): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/sdl/file.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/sdl/file.c.o:(.bss+0x8): multiple definition of `fwrite2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x8): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/video/texture.c.o:(.bss+0x0): multiple definition of `fread2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/Gish.dir/Gish/video/texture.c.o:(.bss+0x8): multiple definition of `fwrite2'; CMakeFiles/Gish.dir/Gish/game/block.c.o:(.bss+0x8): first defined here
collect2: error: ld returned 1 exit status

So almost there, but not quite there! Do you have an idea on why is this happening? Seems like some simple omission, but I don't know what it could be. Any ideas?

[EXL]

Hello, @vanfanel

This is one of the problems in legacy C code with globals in the header files.

GCC now defaults to -fno-common. As a result, global variable accesses are more efficient on various targets. In C, global variables with multiple tentative definitions now result in linker errors. With -fcommon such definitions are silently merged during linking.

https://gcc.gnu.org/gcc-10/changes.html

Quickfix here: 9fd9253.

Cheers!

[vanfanel]

@EXL Whoa, that was fast! I understand the issue now... Thanks!
Time to try this on the Pi! :D

[vanfanel]

@EXL Ooops, I think there was a typo on your fix, look:

[  1%] Building C object CMakeFiles/Gish.dir/Gish/audio/audio.c.o
cc: fatal error: no input files
compilation terminated.
/bin/sh: 1: -fcommon: not found

[EXL]

@vanfanel Hmm, I tested this on Ubuntu 22.04 LTS and it worked.

Please run make in such way for more information about failed command:

make VERBOSE=1

And try to quote the options in CMakeLists.txt:

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fcommon")

[vanfanel]

@EXL Ah, I see, it works if I simply run cmake.
But if I pass CFLAGS like this, it fails:

cmake -DCMAKE_C_FLAGS="-march=native -mtune=native" ..

This is the relevant part in verbose make:

Scanning dependencies of target Gish
make[2]: Leaving directory '/home/manuel/src/Gish/gish/src/main/cpp/b4'
make  -f CMakeFiles/Gish.dir/build.make CMakeFiles/Gish.dir/build
make[2]: Entering directory '/home/manuel/src/Gish/gish/src/main/cpp/b4'
[  1%] Building C object CMakeFiles/Gish.dir/Gish/audio/audio.c.o
/usr/bin/cc  -I/home/manuel/src/Gish/gish/src/main/cpp/Gish -I/usr/include/SDL2 -I/usr/include/AL -march=native -mtune=native;-fcommon -o CMakeFiles/Gish.dir/Gish/audio/audio.c.o -c /home/manuel/src/Gish/gish/src/main/cpp/Gish/audio/audio.c
cc: fatal error: no input files
compilation terminated.
/bin/sh: 1: -fcommon: not found

[EXL]

@vanfanel yep, looks like the quotes are needed.
Damn, I hate CMake.

Please try again with 3a8af8a.

[EXL]

I will be very happy if it works on RPi.

BTW, there was an OpenGL ES renderer which can be enabled by the -DGLES=ON option for CMake.

[vanfanel]

@EXL Now it works with the added CFLAGS!

And yes, it works on the Pi4, too, both in OpenGL and GLES renderers.
OpenGL needs MESA built with GLVND support, since I don't have/want the old GLX.

Performance is very good, too!

EDIT: Forgot to mention I had to disable GLX package searching so it builds on my system (which as I said uses GLVND, not GLX).
Can you please disable mandatory GLX? GLX is a semi-deprecated implementation. Full OpenGL is -lOpenGL (=GLVND) today, not -lGL (GLX) anymore.

[vanfanel]

I am also trying to make this run without X11 (no GLX, no X11) using KMS/DRM on GNU/Linux.
SDL2 has support for KMS/DRM, but you seem to be manually creating an EGL context here:

Gish/gish/src/main/cpp/Gish/main.c

Line 242 in 3a8af8a

eglSurface = eglCreateWindowSurface(eglDisplay, glConfig, (EGLNativeWindowType) sysInfo.info.x11.window, 0);

I think you should let SDL2 create the context, because by doing the manual EGL context creation you are tying the game to the old X11 API.

In other words, PC_GLES is not X11 anymore: it's Wayland, direct KMS/DRM... And SDL2 should take care of it as you do in:

Gish/gish/src/main/cpp/Gish/main.c

Line 246 in 3a8af8a

globalwindow = SDL_CreateWindow("Gish", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,

[EXL]

@vanfanel

Now it works with the added CFLAGS!

Ok, nice!

Can you please disable mandatory GLX? GLX is a semi-deprecated implementation. Full OpenGL is -lOpenGL (=GLVND) today, not -lGL (GLX) anymore.

I think you should let SDL2 create the context, because by doing the manual EGL context creation you are tying the game to the old X11 API.

There is a lot of ancient code in this project. You can make some PRs to update these things if you have the time and desire for that.

I myself want to update the Android build when I have enough time to do so and make it possible for this application to work on modern versions of Android OS without any warnings. Also I want to get rid of some of the bad practices in this code that involve constantly changing the working directory with chdir() to load datafiles.