A simple loader for Dreamcast indie games made with KallistiOS that lets them easily reload or return to a main menu when they call arch_exit(). Without this loader, games would have to manually reload the binary and call arch_exec().
This was made for Dream Disc '24 where I didn't actually realise that calling arch_exit() wouldn't be sufficient, so without this loader we would need to get 10 people to re-submit their games with the addition of manual binary loading and arch_exec() just to return to the menu.
Download dc-reloader.elf from the Releases section and use it with mkdcdisc as follows:
mkdcdisc -e dc-reloader.elf -f main.bin
where main.bin is your own binary. Remember to include any CDDA tracks or data files as usual.
It consists of a simple loader based on the code from the Sylverant PSO Patcher and using a similar mechanism to dc-load-ip.
On load, this program copies itself to 0x8C004000 (AKA. 0xAC004000 in P2) which is unused space in the Dreamcast's memory that lies between the syscalls and IP.BIN. This means it stays in memory regardless of which game is running. It writes its original stack pointer to r15 so that the loaded binary can return to it on exit (something KallistiOS supports).
The KallistiOS gcc-sh4 toolchain is required (tested on version 14.2.0).
mkdcdisc should be available in the user's PATH in order to build the .cdi image.
Just put your main.bin file in the src directory, change to that directory and run make. A CDI file called disc.cdi will be produced. After your menu boots, any subsequent times a program exits using arch_exit(), the menu will be loaded again.
Based on code from Sylverant PSO Patcher by Lawrence Sebald, which includes code from KallistiOS originally by Megan Potter. The file go.s is taken from dc-load-ip (originally by Andrew Kieschnick, since modified/maintained by Moopthehedgehog and SiZiOUS).