Wonder Boy in Monster World - Runahead Single-Instance mode causes game to freeze on Save

[msheehan79]

Windows 11 x64
RetroArch 1.22.2
Core Build 162c343
Game: Wonder Boy in Monster World (USA, Europe)

If Runahead Single-Instance is enabled, when attempting an in-game Save at the Innkeeper the game will freeze. Music will continue to play but otherwise game is unresponsive. With Runahead disabled the EEPROM save works as expected.

[msheehan79]

Confirmed the issue is due to the I2C EEPROM not being serialized in the current core. A test build where I added it to the state fixes the issue (msheehan79@62f6801), but I assume making this change would break existing save states so I'm not sure if there is a better way to handle this that wouldn't invalidate older state files.

Or, just use preemptive frames/second instance mode I guess.