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Date: Thu, 3 Jun 2010 17:40:49 -0400 (EDT)
From: Benjamin Kaduk <kaduk@MIT.EDU>
To: David Rhodus <sdrhodus@gmail.com>
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Subject: Re: Auto doadump()
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On Thu, 3 Jun 2010, David Rhodus wrote:

> Is there a rc.conf variable to automatically save core on a panic and reboot ?
> Setting dumpdev="AUTO"  doesn't seem to do the trick.

dumpdev merely controls which swap device the dump gets written to.
You probably want to either compile your kernel with KDB_UNATTENDED or set 
the debug.debugger_on_panic sysctl to 0.
(I run my systems to drop into KDB interactively, but reading 
kern/kern_shutdown.c seems to indicate that this will do what you want.)

-Ben Kaduk