Posted by hans2 on Mar 04, 2016; 10:10pm
URL: https://itus.accessinnov.com/Anyone-know-how-to-use-the-SD-Card-for-storage-or-ram-tp270p290.html

Stage 3 boot has the commands you need:

PCIe: Link timeout on port 0, probably the slot is empty
PCIe: Port 1 not in PCIe mode, skipping
PCIe: Port 2 not in PCIe mode, skipping
Net:   cvmx_helper_interface: interface 0
cvmx_helper_interface: interface 1
cvmx_helper_interface: interface 4
octeth0, octeth1, octeth2, octeth3
Type the command 'usb start' to scan for USB storage devices.

late_board_init ..
ITUS: SW1 1 Bridge (INNER)
Hit any key to stop autoboot:  0
Octeon cust_private_rhino_itus7x(ram)#

here are the commands available in stage 3: boot_stage3_CLI.txt

but I've never tested it.