Hello,

I'm interested in using sysctl to control some of the parameters of the
mac's serial driver. I want to use sysctl to change a per-port
parameter (having to do with hardware flow control and our mixing of
DTR & RTS on the same pin).

I've looked at the sysctl code a couple of times, and it's making a
little more sense. Unfortunately, as far as I can tell, the sysctl
program gets its name mib from grovveling in the sys include files.
For items whose count is defined either at config time or at
attach time, I don't see how sysctl could be used, except possably
by defining a larger-than-needed count in the header, and having
all the unattached units come up with an "unattached" value.

As an example, the mac port supports two types of crtscts flow
control. The first is for modems, where we shut up when CTS says,
and we use DTR to hang up the modem. The second is where we use CTS
and DTR (in place of RTS) for handshaking. RTS is unavailable as it
drives the transmit trancievers. 

What I'd like to do is add to sysctl something like:

machdep.zstty.flow_type.tty00=0
machdep.zstty.flow_type.tty01=1
machdep.zstty.flow_type.tty02=0 (for machines with serial boards).
etc.

Suggestions?

Thanks!

Bill