This looks promising:
https://github.com/geekmaster/dxg-di...sb/composite.h
A USB composite device driver for the kindle would allow it to provide RNDIS usb networking AND shared USB mass storage
at the same time.
It seems to be used in this DXG loadable kernel module for making a kindle DXG appear as a "displaylink" USB video device for a host PC.
More info here:
http://how-to.cc/get-a-displaylink-v...h-ubuntu-12-04
The K1 kernel supports 3G networking over USB serial (attached to the internal 3G radio modem), so perhaps it would also support an RNDIS (g_eth) driver as well? In that case USB shared-file root shell is less necessary (but still an interesting project), in cases where shared files are the only available form of communication (BBS or "mailbox" style messaging), though a shared RAM disk would be preferable to actually writing to flash. There are lots of options open to the imagination...