Watching serial port activity.
grante at visi.com
Tue May 30 20:09:49 CEST 2006
On 2006-05-30, Cameron Laird <claird at lairds.us> wrote:
>>If you feel like building a kernel, adding a few printk() calls
>>to either the low-level serial driver or the tty
>>line-discipline layer might do what you want.
> !? I hadn't realized there's no such monitor ... What do you
> think of <URL: http://wiki.tcl.tk/moni >?
It's yet another a terminal program (written in TCL).
_If_ the pty device didn't force parity=None and bits=8, and
_if_ it implemented the modem control/status ioctl() calls, and
_if_ it went through the line discipline layer like a real
serial port does, then something like slsnif would be workable
for "real" serial port applications.
In a more general sense, it would mean you could actually
simulate a serial port with user-space code. That allows you
to do cool stuff like create virtual serial ports in user-space
that are connected via Ethernet to physical (or virtual) serial
ports on other hosts. [OK, I admit there are only a few of us
who think that's a cool thing to do.]
Currently, if you want to create a virtual serial port under
Linux you have to write a kernel-mode device driver. The only
practical way to do that is to write a virtual "low level"
serial driver that uses the line-discipline layer in the normal
manner. And that's a real bitch to maintain because the API
between the line-discipline layer and the driver you've just
written is constantly changing (it seems to get major overhauls
even between minor versions of a "stable" kernel).
Someday I'll write a pty driver that actually allows simulation
of a serial port...
Grant Edwards grante Yow! .. My pants just went
at on a wild rampage through a
visi.com Long Island Bowling Alley!!
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