The A10 boots from USB as the last device on the boot chain after the SD card and NAND. However, it boots directly to USB if the recovery button has been pressed. That is what allows you to load an new image to the flash from LiveSuit.
If there is a way to permanently enable recovery mode then it may be possible to always boot from USB. That would open the possibility of booting directly from huge, fast external USB drives. The USB bus would be a bottleneck, but the Dockstar and other Kirkwood devices have proven that USB boot is a huge advantage and saves the internal flash from wear.
Another way to boot from USB would be to remove the bootloader from NAND, and not have a bootloader on the SD card. Then the device would boot directly from USB. I don't really like the idea of removing the bootloader from NAND, but we always have a spare SD to boot from if all else fails :)
Edit:
Currently USB is for "FEL recovery" only - using LiveSuit or another recovery tool. U-boot for the A10 currently does not support USB.
Edited 2 time(s). Last edit at 07/21/2012 05:44PM by gnexus.