Hello,
  this is my first contribution, so I'm basically requesting for comments.

The attached patch adds support for Archos G9 tablet wich uses an OMAP4460
cpu.
The tablet by default only boots from internal flash, so to test barebox on
it
a hardware tweak is required: change the sys_boot configuration.
Once done the tablet can be booted with the following command:
 sudo scripts/usbboot <first_stage> <rootfs>

The patch contains
 1.- specific changes for OMAP4460
 2.- support for usb-booting
 3.- support for console on usb
 4.- support for file transfer through usb
 5.- some minor bug fixes
 6.- adds support for archosg9 board

A question I have is what does omap_vector_init do?
It breaks usb-booting.

In any case the patch should be tested with other boards to check it does
not
breaks something.

The patch applies against 1af6fdcd03dbc311d785625bd6e2329f7ce1adb7.

Thanks,
  vicencb