How to enter DDB through a terminal server / remote console ... ?

Andrew Thompson thompsa at
Wed Jun 28 22:40:18 UTC 2006

On Wed, Jun 28, 2006 at 07:34:43PM -0300, User Freebsd wrote:
> On Wed, 28 Jun 2006, Robert Watson wrote:
> >On Wed, 28 Jun 2006, User Freebsd wrote:
> >
> >>'k, now that I'm up to 3 6-STABLE servers that are deadlocking, I'm 
> >>spending time with the remote tech today to get a serial console put 
> >>online ... how do I drop into DDB remotely, where the serial console is 
> >>going through a Portmaster Terminal server?  issuing CTL-ALT-ESC, I 
> >>doubt, will work, will it?
> >
> >If configured to use a serial console (console="comconsole" in 
> >loader.conf), you can enter the debugger with BREAK_TO_DEBUGGER in the 
> >kernel config by sending a serial break.  With my portmasters, I telnet to 
> >a TCP port to connect to the serial console, so I send a telnet break, 
> >using ^]send break.
> Have you ever had a problem with this warning: "(useful for remote 
> diagnostics, but also dangerous if you generate a spurious BREAK on the 
> serial port!)" in the handbook?
You can use ALT_BREAK_TO_DEBUGGER which uses the CR ~ ^b sequence if you
are worried about stray breaks.


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