[U-Boot] Dumb question: is UMS/MASS_STORAGE_GADGET in SPL possible?

[Jason Kridner]

I'm trying to make a small image enabling u-boot UMS mode on BeagleBone
Black against the on-board eMMC. Is it possible to enable UMS simply within
SPL?

It seems like some others have done it in the past (
http://lists.denx.de/pipermail/u-boot/2015-March/207600.html), but I don't
see an obvious way to enable it.

Performance might not be great (
https://boundarydevices.com/u-boot-usb-mass-storage-gadget/), but
minimizing the user steps could make it worth doing it in u-boot
(preferably SPL) than to load a kernel and ramdisk (
https://github.com/ungureanuvladvictor/BBBlfs).