USB port not functional by default
According to Apple, the USB connector on the Apple TV is reserved for Apple support only. However, given that Command-S will boot it into single user mode it seems unlikely that they've disabled the port at the hardware level.
USB port visible in the OS
The system_profiler included with the AppleTV sees the USB, and has a 1.1 and 2.0 driver attached. USB devices attached to the port are also seen by system_profiler:
USB: USB High-Speed Bus: Host Controller Location: Built In USB Host Controller Driver: AppleUSBEHCI PCI Device ID: 0x27cc PCI Revision ID: 0x0002 PCI Vendor ID: 0x8086 Bus Number: 0xfd USB Bus: Host Controller Location: Built In USB Host Controller Driver: AppleUSBUHCI PCI Device ID: 0x27c8 PCI Revision ID: 0x0002 PCI Vendor ID: 0x8086 Bus Number: 0x1d Bluetooth HCI: Version: 5.25 Bus Power (mA): 500 Speed: Up to 12 Mb/sec Product ID: 0x0001 Vendor ID: 0x0a12 IR Receiver: Version: 2.42 Bus Power (mA): 500 Speed: Up to 1.5 Mb/sec Manufacturer: Apple Computer, Inc. Product ID: 0x8241 Vendor ID: 0x05ac (Apple Computer, Inc.)
Mounting filesystems from USB Mass Storage Devices
Obviously this is the number one thing we'd like to get working with USB. I need to trace how diskarbitrationd works and how new USB storage devices get probed and mounted.
One possibility is that the diskarbitrationd distributed with the AppleTV is limited to mounting filesystems off the boot device of the unit, or the IDE interface. If someone with MacOS 10.4.7 could run 'md5 /usr/sbin/diskarbitrationd' and compare it to the appletv's:
MD5 (/usr/sbin/diskarbitrationd) = 493e88e3db210ef0557a2c48e1214a8b
we could begin to narrow things down.
Mac OS X 10.4.7 Comparisons
Mac OS 10.4.7, Intel Mac mini basic install. For more information see the discussion page.
md5 /Volumes/Bootcamp\ Master/usr/sbin/diskarbitrationd MD5 (/Volumes/Bootcamp Master/usr/sbin/diskarbitrationd) = ac17cc6c4d0e795b44fb1120f508c23a
How to enable USB ports
Initial progress has been made to enable USB. (Initially, some people have tried swapping IOUSB files, but that didn't work, because there is another set of files in mach_kernel.prelink which also need to be changed.)
http://0xfeedbeef.com/appletv/ claims "USB success" - more information here as it unfolds.
Command-S boots single user mode
However, the USB port is fully functional hardware-wise:
Plug a keyboard in and press Command-S during startup will start up in Single-User mode.
Boot from USB drive
Ozy used a cloned internal drive where he changed the boot picture in order to distinguish it from the internal drive. Since the Apple TV OS disables USB during the boot process, it doesn't fully boot. But hey, it's a start, isn't it? Next we'll make a Darwin mini USB drive image...