USB serial port vs 6.1

[perryh at pluto.rain.com]

> > Does 6.1 have some fundamental problem with USB serial devices?
>
> No (but you ought to update to 6.3).

Someday, maybe, but at this point I may just wait til 7.0 comes out :)

> > I'm trying a USB-serial converter after getting nowhere with
> > connecting a USB modem directly -- the modem also has a DB9 --
> > and getting the same unexpected behavior from the converter as
> > from the modem.
> > 
> > When connected, the console reports:
> > 
> > ugen0: FIDI usb serial converter, rev 1.10/4.00, addr 3
...
> These device nodes are created by ugen(4), which is not what you want.
>
> You need to load the uftdi(4) kernel module before plugging in the
> FTDI based USB<->RS-232 device. That driver should create a /dev/ttyU0
> or similar named device node.

Yes, the console now reports

  ucom0: FIDI usb serial converter, rev 1.10/4.00, addr 3

and /dev contains:

  crw-rw----  1 uucp  dialer    1,  23 Nov 24 21:17 /dev/cuaU0
  crw-rw----  1 uucp  dialer    1,  24 Nov 24 21:17 /dev/cuaU0.init
  crw-rw----  1 uucp  dialer    1,  25 Nov 24 21:17 /dev/cuaU0.lock
  crw-------  1 root  wheel     1,  20 Nov 24 21:17 /dev/ttyU0
  crw-------  1 root  wheel     1,  21 Nov 24 21:17 /dev/ttyU0.init
  crw-------  1 root  wheel     1,  22 Nov 24 21:17 /dev/ttyU0.lock

so apparently the combination of uftdi and ucom picked it up.
(I already had ucom loaded from the earlier attempt to get the
modem recognized as a USB <==> serial device.)

Short of guesswork, or loading everything, how would one go about
figuring out which of the various uxxx shims is going to be needed
to connect a given serial device to ucom?  I notice that "man uftdi"
does not mention "FIDI" (granted "FTDI" is close).