ttyd0/cuad0 - why is there still this duality ?

[Bernd Walter]

On Mon, Jan 24, 2005 at 12:42:50PM -0500, Kurt J. Lidl wrote:
> On Mon, Jan 24, 2005 at 04:16:13PM +0100, Bernd Walter wrote:
> > On Mon, Jan 24, 2005 at 09:30:43AM +0100, Christoph P. Kukulies wrote:
> > > Just a question. Maybe it isn't true but to me it seems there
> > > is still this duality between ttyd and cuad serial devices.
> > > 
> > > Why is that? I'm just asking because someone I was talking with 
> > > about modems an comm programs was 'criticising' this fact
> > > in FreeBSD "while other systems long have abandoned this dualism"?
> > 
> > Because modems are still used for dial-in and dial-out.
> > tty handing out to getty and cua to the dial out process.
> > Moreover this handling was recently added for usb serials under
> > -current.
> > If other systems loose features - well it's their problem.
> 
> That's a very limited way of looking at the functionality.  If you
> want to support the functions of both dialin and dialout on one
> serial port, there doesn't need to be more than one kernel device.
> Just because support for this got hacked into 4.2BSD in a gross
> manner doesn't mean that there isn't a better of doing this.

You still have the option to just ignore existenz of tty* devnodes.

> Having seperate dialout and dialin devices really are just a kludge
> for having the kernel doing locking that could be done in userland
> code.

tty* vs cua* is more than just locking.

> Just because FreeBSD does this the same way it's been done on
> BSD-ish systems for the last 15 years doesn't mean there isn't a
> better way of doing it.

Yes, but this way it just works and applications used it for many
years.

-- 
B.Walter                   BWCT                http://www.bwct.de
bernd at bwct.de                                  info at bwct.de