Date: Sun, 2 Feb 2003 19:56:41 -0800 From: "Maksim Yevmenkin" <Maksim.Yevmenkin@cw.com> To: "M. Warner Losh" <imp@bsdimp.com> Cc: <hackers@FreeBSD.ORG>, <questions@FreeBSD.ORG> Subject: RE: PPP in -direct mode does not execute any chat scripts Message-ID: <45258A4365C6B24A9832BFE224837D552B1286@sjdcex01.int.exodus.net>
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Warner,
> Is there any reason that RFCOMM doesn't give full tty support, like
> the various USB modem drivers do? That's likely the best way to deal
> with this. Then ppp or whatever application you want will just work.
Yes, there is. RFCOMM connection can only be established when
baseband link is open. Also RFCOMM connection exists between
pair of device and identified by source address, destination
address and channel. In fact up to 60 RFCOMM channels can exist
on the same baseband link between the same pair of devices.
So, with tty device things look a bit weird. for example if
user wants to dial out then user must do three things:
1) establish binding between source, destination address, channel
and particular tty device;
2) open RFCOMM channel on the tty device;
3) start PPP on the tty device.
Things gets even more tricky when you want to run server
on specific RFCOMM channel. In this case tty device does not
exist at all until RFCOMM connection is establised. So it is
really hard to do binding between connection and tty device.
May be if we could clone tty devices then if would be easier.
Also Bluetooth spec. has redefined some aspects of GSM 07.10
spec. and all Bluetooth 1.1 devices do not use modem signals
defined in GSM 07.10. Instead there is something called=20
'credit based flow control'.
So you see it is probably possible to build a tty-like interface,
but i do not think it really worth the trouble. In fact one
can do it right now with the help of nmdm(4) driver. It is a
simple wrapper that would pass the data between socket and
/dev/nmdm0{A|B}.
thanks,
max
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