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Date:      Fri, 12 Jan 2024 13:45:04 -0800
From:      Mark Millard <marklmi@yahoo.com>
To:        bob prohaska <fbsd@www.zefox.net>
Cc:        freebsd-arm@freebsd.org
Subject:   Re: USB-serial adapter suggestions needed
Message-ID:  <B3EF009B-F7FE-4D2D-A266-D064C82E0DFF@yahoo.com>
In-Reply-To: <ZaGxMA23qXBSC4Jj@www.zefox.net>
References:  <55AC6824-587D-4C67-B64B-2045A1112F69@yahoo.com> <ZZ8ugUkEDXbSUjZp@www.zefox.net> <041F74B4-3D44-4364-9EBD-9F21A4F3B313@yahoo.com> <ZaBLnwaHWYedwY9m@www.zefox.net> <902798B1-2B66-4ECD-BDAC-195C85066FE6@yahoo.com> <8B4C76B2-707E-4978-9CB3-5D547303A7E5@yahoo.com> <ZaFoY58MqBv9hX5b@www.zefox.net> <A1F3092A-CEB1-44DE-ADB3-F45113004B34@yahoo.com> <ZaGQfy8u2xYzztri@www.zefox.net> <482FA770-89E8-42E8-945E-B662AD564AFE@yahoo.com> <ZaGxMA23qXBSC4Jj@www.zefox.net>

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On Jan 12, 2024, at 13:37, bob prohaska <fbsd@www.zefox.net> wrote:
>=20
> On Fri, Jan 12, 2024 at 12:38:30PM -0800, Mark Millard wrote:
>> On Jan 12, 2024, at 11:18, bob prohaska <fbsd@www.zefox.net> wrote:
>>=20
>>> On Fri, Jan 12, 2024 at 10:34:11AM -0800, Mark Millard wrote:
>>>>=20
>>>> If you did not specify the signal explicitly, you tried:
>>>>=20
>>>>    15    SIGTERM          terminate process    software termination =
signal
>>>>=20
>>>> (I'm not claiming all those "terminate process" signals are
>>>> likely to be involved. But SIGTERM is need not be involved
>>>> at all.)
>>>>=20
>>>>> Both the ssh connection from workstation to terminal
>>>>> server and the su to root needed to run tip survive.
>>>>>=20
>>>>> I should apologize for not testing this sooner, it
>>>>> was a very easy experiment. If you think of useful
>>>>> variations please indicate them.
>>>>=20
>>>> See above, in particular SIGHUP .
>>>>=20
>>>=20
>>> Just tried SIGHUP several times. The ssh connection didn't
>>> disconnect. There were also no reports about overriding stale
>>> locks.=20
>>>=20
>>> Using SIGKILL reported:
>>>=20
>>> login: Killed
>>>            root@nemesis:/home/bob #=20
>>> root@nemesis:/home/bob # tip ucom
>>> Stale lock on cuaU0 PID=3D45604... overriding.
>>> connected
>>>=20
>>>=20
>>> FreeBSD/arm (ns2.zefox.net) (ttyu0)
>>> but the ssh session and su survived.
>>>=20
>>> Finally, I tried SIGSTOP. Again, ssh and su stayed up, but
>>> restarting tip reported:
>>> all ports busy
>>> Power-cycling the usb-serial adpter with usbconfig
>>> isn't able to free the port. That's new-to-me behavior.
>>> Deleting the /dev/cuaU0-related files didn't help.
>>>=20
>>> Not sure what to make of this, except that ssh survives
>>> exit of tip, graceful or not. =20
>>=20
>> Remember:
>>=20
>> Jan 10 14:29:48 nemesis kernel: ucom_close: tp=3D0xffffa00001979800
>> Jan 10 14:29:48 nemesis kernel: ucom_shutdown:=20
>> Jan 10 14:29:48 nemesis kernel: ucom_dtr: onoff =3D 0
>> Jan 10 14:29:48 nemesis kernel: ucom_line_state: on=3D0x00, off=3D0x01
>> Jan 10 14:29:48 nemesis kernel: ucom_rts: onoff =3D 1
>> Jan 10 14:29:48 nemesis kernel: ucom_line_state: on=3D0x02, off=3D0x00
>> Jan 10 14:29:48 nemesis kernel: ucom_cfg_close:=20
>> Jan 10 15:04:07 nemesis su[35181]: bob to root on /dev/pts/4
>>=20
>> (and what was somewhat before and somewhat after)?
>>=20
>> What were those messages like (if any) for each of the types of =
kills?
>=20
> Far as I can tell they're the same following ucom_shutdown.=20
> Preceeding ucom_shutdown it looks like the sequence of messages
> varies a little, but obvious things like the big hex numbers
> are clearly indentical.=20
>=20
> If you've got something in mind please tell me what it is and I'll=20
> be able to look more intelligently.

So each of the signals result in a full

ucom_close: tp=3D. . .
. . .
ucom_cfg_close:

sequence?

If yes, that answers my question. Otherwise I'd like to=20
see the variations.

=3D=3D=3D
Mark Millard
marklmi at yahoo.com




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