The dump will go to /mnt/asec/ folder in .bin format (the name of the cartridge dump tested was rom-9370.bin).
The name can be related to some hex values inside the cartridge (for example 2 bytes at offset 0x18E) because the cartridge name is always the same using the same cartridge (unfortunately I only have 1 to play with).
This is the dmesg information of the dumping process:
and then it stops. The dump procedure seems to start ad 15.435434 seconds from the console boot (after mtp_open) because this is the dmesg WITHOUT the cartridge inserted:
Can you explain what you did to succesfully connect an usb flashdrive ? Did you use a self-powered adapter ?
Can you also tell me the full path of the usb flash drive once mounted ? Is it /mnt/usb_storage/ as I suppose ?