weird Ctrl-T debug messages

[John Baldwin]

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.

-- 
John Baldwin