force panic of remote server ... possible?

[Ed Maste]

On Mon, Jun 26, 2006 at 01:06:14PM +0100, Gavin Atkinson wrote:

> On Mon, 2006-06-26 at 08:55 -0300, Marc G. Fournier wrote:
> > For the server that I'm fighting with right now, where Dmitry pointed out 
> > that it looks like a deadlock issue ... I have dumpdev/savecore enabled, 
> > is there some way of forcing it to panic when I know I actually have the 
> > deadlock, so that it will dump a core?
> 
> You cen enter the debugger by setting the (badly names) debug.kdb.enter
> sysctl to 1, although I can't guarantee that'll trigger a dump and
> reboot.  Do you have a serial console?

>From some of your other messages, I believe this is a remote machine?
Unless you can access an attached keyboard, or have a serial console,
debug.kdb.enter will leave the machine sitting in ddb with no way to
get out.  Also, if you have a PS/2 keyboard (that is, one handled by
the atkbd(4) driver) ddb will not accept any input on 6.1 or HEAD.
(There is some discussion of this issue on the freebsd-current list.)
Before using ddb on a remote machine I would suggest testing it out
with the same release locally.

For your original question -- I'm not sure which release it first
appeared in (and it may be only in -CURRENT), but if it exists you
can use:

$ sysctl -d debug.kdb.panic
debug.kdb.panic: set to panic the kernel

-ed