Subject: Re: Serial Port Strangeness.
To: Perry E. Metzger <>
From: Bill Studenmund <>
List: current-users
Date: 09/09/1997 12:47:19
On Tue, 9 Sep 1997, Perry E. Metzger wrote:

> Dave Burgess writes:
> > I asked this on the port-i386 list, and got a couple of answers - one of
> > which makes me wonder it this might not be a problem across the
> > platforms.
> > 
> > I'm working on mgetty with the 1.2G tar 'non-release' from last month.
> > Whenever I use the TIOCMGET ioctl on the /dev/tty0* ports, I get an
> > [ENOTTY] error.  The rest of the TIO ioctls I tried all work (some of
> > them only sort of, but they don't error out).
> As a wild guess, do you have COMPAT_43 in your kernel config?

The answer's far simpler. TIOCM* support disapeared with one of the serial
port upgrades. Quoting /sys/dev/isa/com.c sup'd last week,

comioctl(dev, cmd, data, flag, p)
        dev_t dev;
        u_long cmd;
        caddr_t data;
        int flag;
        struct proc *p;


        switch (cmd) {


        case TIOCMSET:
        case TIOCMBIS:
        case TIOCMBIC:
        case TIOCMGET:
                return (ENOTTY);
	return (0);

They used to be there, as I used them as a model for adding such support
to the z8530tty driver.

Sounds like a good candidate for a PR.

Take care,