PDBoot

A simple boot shim that merely launches another playdate application. This can be used as part of, for example, a self-updater.

Limitations

• Only works with Pure-C playdate games. Cannot load Lua games.
• The launched playdate application must be specially compiled, and built separately for rev A and rev B devices.
• Heap size must be specified in advance. This forces a limit on the size of the program to be loaded.

How to use:

First, build pdboot:

make -j 4

(Note: replace MyGame.pdx with your actual pdx)

# create .pdb for rev A:
python3.11 elfboiler/elfboiler.py Source/pdex.elf MyGame.pdx/appA.pdb 0x60000000

# create .pdb for rev B:
python3.11 elfboiler/elfboiler.py Source/pdex.elf MyGame.pdx/appB.pdb 0x90000000

# replace .bin with pdboot:
cp path/to/pdboot/PDBoot.pdx/pdex.bin MyGame.pdx/pdex.bin

If you then run MyGame.pdx on a playdate device, it should launch via pdboot. You can check the output log in the simulator to confirm; pdboot should print some messages.

Troubleshooting

If elfboiler.py is failing, most likely you are using a type of relocation symbol that hasn't been implemented yet. You can try implementing it based on the documentation linked in the output of elfboiler.py, or you can change compile settings. Try using gcc, and don't use -fPIC (position-independent code).

Extra features:

If you include pdboot.h, you can access some data about pdboot, which is stored at the address returned by playdate->graphics->getFrame(). If the magic field matches the string in the header, then that means the game has been launched by pdboot. Otherwise, pdboot was not involved in launching the game.