Fatal Trap 12 in various processes always at address 0x3030313a

[Richard Mahlerwein]

--- On Sun, 8/30/09, Gavin Atkinson <gavin at FreeBSD.org> wrote:

> From: Gavin Atkinson <gavin at FreeBSD.org>
> Subject: Re: Fatal Trap 12 in various processes always at address 0x3030313a
> To: "Richard Mahlerwein" <mahlerrd at yahoo.com>
> Cc: "FreeBSD-Stable" <freebsd-stable at FreeBSD.org>
> Date: Sunday, August 30, 2009, 3:47 PM
> On Sat, 29 Aug 2009, Richard
> Mahlerwein wrote:
> 
> > (Sorry, update to subject to be <something>)
> > 
> > 3 weeks ago:
> > I upgraded from 7.1-PRELEASE to -stable and all seemed
> fine
> > until I rebooted out of single user mode after doing
> make
> > installworld and mergemaster.  At that point, near
> the
> > end of the boot sequence I got a core dump,
> apparently
> > triggered by devd.
> > 
> > ****
> > Fatal trap 12: page fault while in kernel mode.
> > cpu id = 0; apic id = 00
> > fault virtual address = 0x3030313a
> > fault code = supervisor write, page not present
> > [snip]
> > current process = 355 (devd)
> > ****
> > 
> > [snip]
> > Does anyone have a further recommendation on what to
> do,
> > try, test or change?
> 
> Firstly, please set up a dump partition by adding
> 'dumpdev="AUTO"' to your rc.conf.
> 
> Then, can you compile in the kernel debugger (options KGB /
> options DDB) and when this happens again, please obtain a
> backtrace from the debugger with the "bt" command. 
> Then, give the "show registers" command so that we can
> establish which register is pointing to the odd address.
> Finally, issue the "call doadump()" command to hopefully
> save a copy of the kernel dump for later analysis.
> 
> Thanks,
> 
> Gavin

No problem, but for future reference by others reading this thread, the handbook says KGB should be KDB, which is what I'm enabling in the kernel config.  DDB is fine.

http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug-online-ddb.html