USB2 - umass problem
nick at anywi.com
Mon Feb 9 01:47:37 PST 2009
> : > By some reason devfs semantic was changed:
> : > Instead of /dev/cuaU0.[0-2] and /dev/ttyU0.[0-2], I've get
> : > /dev/cuaU[0-2] /dev/ttyU[0-2] and! /dev/cuau1 /dev/ttyu1
> : > What is reason for such change (additional port with lowercase 'u'
> : > and U[0-2] instead of more logical U0.[0-2]) ?
> : It is because we are attaching drivers per interface instead of per
> : device. A new modem unit is allocated every time we find a modem,
> : simply put. If the modem has multiple instances in an interface,
> : /dev/cuaU0.[0...] will be created. Else /dev/cuaU... .
> Generally, we try not to change the details of how a device attaches
> /dev entries from release to release. Why the change?
The USB1 u3g driver also attaches to interfaces, but collects all interfaces
in one go, leaving all unused interfaces available for other drivers (e.g.
umass) or claims them (to hide the 'driver disks'). It is the main reason
why I wrote a separate driver in the first place. Otherwise the UMTS cards
could be treated as serial ports without any port singalling.
It is important to be able to determine in an automated way the 2 or more
serial ports that belong together. As an example: If you create a router
box that automatically configures itself depending on the hardware it
finds, we somehow need to find out which two serial ports are found on each
GPRS/UMTS card, so we can assign the first one to PPP and the other one to
our control application.
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