Re: serial console and panic

[Christoph Egger <Christoph_Egger%gmx.de@localhost>]

Thomas E. Spanjaard wrote:
> Christoph Egger wrote:
>> Emmanuel Dreyfus wrote:
>>> Christoph Egger <Christoph_Egger%gmx.de@localhost> wrote:
>>>
>>>> Looks like, there's a relation to PR kern/40734.
>>> Yes, it looks similar. 
>>> Any workaround? Does that help if I disable the console in /etc/ttys,
>>> for instance?
>>>
>> From last time it happened to me
>> I have the suspicion, that unplug and
>> then re-plug the serial connector may cause this.
> 
> If there is an earthing potential difference between the two machines
> connected with a serial (RS232/null-modem) cable, the resulting
> (mini-)surge will be interpreted as a break signal. You can prevent it
> by using special cables or wiring a resistor between the ground
> connections (iirc). Another workaround is to not have a break signal
> trigger DDB (I think there's a sysctl for that).

This "break signal" triggers a dereference of a NULL-pointer in
comintr().

Christoph