Re: panic in devfs_populate_loop()

On Wed, 2005-11-02 at 15:05 -0500, Kris Kennaway wrote:
> On Wed, Nov 02, 2005 at 04:57:53PM +0100, Stefan Ehmann wrote:
> > After todays cvsup and buildworld/kernel I get a panic during boot.
> > 
> > Kernel from October 29th works fine. Maybe related to the latest ACPI-CA
> > import.
> > 
> > Panic string and backtrace hand-transcribed.
> > 
> > Fatal trap 12: page fault while in kernel mode
> > 
> > devfs_populate_loop()
> > devfs_populate()
> > devfs_lookup()
> > VOP_LOOKUP_APV()
> > lookup()
> > namei()
> > kern_symlink()
> > devfs_first()
> > vfs_mountroot()
> > start_init
> > fork_exit()
> > fork_trampoline()
> 
> You'll need to obtain further debugging information (i.e. crash dump)

I cannot get a dump because the panic happens before dumpon is executed.

The handbook says this about obtaining a crash dump:
"Alternatively, the dump device can be hard-coded via the dump clause in
the config(5) line of a kernel configuration file. This approach is
deprecated and should be used only if a kernel is crashing before
dumpon(8) can be executed."

Unfortunately I could not figure out how to do this. Google only found
http://lists.freebsd.org/pipermail/freebsd-current/2005-April/049465.html
but that's not very helpful.