weird Ctrl-T debug messages

[Warner Losh]

On Sat, Jun 27, 2020 at 8:50 AM Michael Gmelin <freebsd at grem.de> wrote:

>
>
> On Sat, 27 Jun 2020 06:21:17 -0700
> John Baldwin <jhb at FreeBSD.org> wrote:
>
> > On 6/27/20 2:59 AM, Michael Gmelin wrote:
> > >
> > >
> > > On Sat, 27 Jun 2020 12:06:17 +0300
> > > Andriy Gapon <avg at FreeBSD.org> wrote:
> > >
> > >> On 27/06/2020 10:44, Li-Wen Hsu wrote:
> > >>> On Sat, Jun 27, 2020 at 3:04 PM Hartmann, O.
> > >>> <ohartmann at walstatt.org> wrote:
> > >>>>
> > >>>> Running poudriere on recent CURRENT with (recent) 12-STABLE and
> > >>>> CURRENT jails reveals a weird behaviour recently when hitting
> > >>>> Ctrl-T:
> > >>> ...
> > >>>> Is this debug fallout from /bin/sh?
> > >>>
> > >>> It's because kern.tty_info_kstacks is on by default now:
> > >>>
> > >>> https://svnweb.freebsd.org/changeset/base/362141
> > >>
> > >> May I suggest that the stack trace is printed procstat -kk style
> > >> (single line) ? I think that the more compact output would be more
> > >> convenient.
> > >
> > > It's a cool feature and having it on by default on CURRENT certainly
> > > helps to discover it, which is great. Thanks for implementing this!
> > >
> > > I wouldn't enable it by default on RELEASE versions though, as
> > > CTRL-T is a user interface to get status information (at least this
> > > is how I use it personally, e.g., while running commands like
> > > dd[0], cp, mv, poudriere etc.), not for getting debug output.
> >
> > I agree with this.
> >
> > > Question: Speaking of discovering the feature, wouldn't it make
> > > sense to document this tunable on the stack(9) and/or tty(4) man
> > > page(s)?
> >
> > This sounds like a great idea.  Would you able to come up with a
> > patch? I'd be happy to review it.
>
> Sure, it actually seems like that termios(4) is the best
> place to put this information.
>
> https://reviews.freebsd.org/D25488


Damn, when I read this, I thought it was patches to control this on a
per-tty basis by putting it in termios... That would be even cooler :)

Warner