TBH, I could not find those checks you mentioned in the code. Before started this Thread, I actually experimented on this issue (in the klipper module and in the linux mcu). The way I understand the init routine on a linux mcu, it does not bother if a slave host controller (i2c-lalala) is present. That’s why I’m not sure about your statement that “the code does check that the device exists upon initialization”. I just could not find those checks in the code. (I’m new to the code so I’d really be glad if you could point me to the right place to look at!)