9->10: USB device number changes

[Gary Palmer]

On Sat, Jan 04, 2014 at 04:41:43PM +0000, Christian Weisgerber wrote:
> If you're going from FreeBSD 9 to 10, the attach order of USB devices
> may change.
> 
> FreeBSD 9's GENERIC kernel has various USB drivers compiled in.  On
> 10, only a few core drivers remain in GENERIC and drivers for other
> devices are loaded dynamically as kernel modules by devd(8).  As a
> side effect, the attach order and thus the numbering may change.
> 
> Specifically, I have four ucom(4) adapters on a machine, a mix of
> three uplcom(4) and one uftdi(4) device.  On FreeBSD 9, these used
> to attach in the USB address order.  On 10, the uplcoms all attach
> first, in address order, and the uftdi afterwards, so the corresponding
> devices cuaU[0-3] have been reordered.
> 
> I just thought I'd mention it.

Can we wire down USB buses and devices like we can with CAM?

e.g. for CAM

hint.scbus.0.at="ahcich0"                                                       
hint.scbus.1.at="ahcich1"                                                       
hint.ada.0.at="scbus0"                                                          
hint.ada.1.at="scbus1"                                                          

(etc)

If not, it would be nice to have that feature.

Gary