I wrote that guide, so if there are any issues with it please let me know here.Still investigating/documenting this issue, while awaiting feedback from people in-the-know.
Finally found some great and recent official Pi Ltd whitepaper on OTG modes.
Specifically for mass storage it states:Now, it still does not say if stall=0 is required (while now officially blessed), nor any reason why...Code:
options g_mass_storage file=/drive.bin stall=0 removable=1
Reference BCM2835-ARM-Peripherals doc did not help yet shedding light on this unfortunately (p 200+).
There's probably something lying in BCM2835/Synopsys usb/udc driver (bug/stall=0 not enforced by default)...
Thoughts?
Can't say whether it's required or not but I don't recall ever including stall=0 when I've used that gadget nor do I recall mentioning it in USB Mass Storage Gadget - A Beginner's Guide.
As for removable=1 that's definitely not required. It's for emulating things like SD card readers where you can hot swap the card. Or if you want to be able to change the backing store from the Pi without unloading and reloading the module (or want to load the module without initially specifying a backing store).
Statistics: Posted by jamesh — Sat Jan 17, 2026 5:40 pm