debugging frequent kernel panics on 8.2-RELEASE

[Steven Hartland]

We're currently experiencing a large number of kernel panics
on FreeBSD 8.2-RELEASE across a large number of machines here.

The base stack reported is a double fault with no additional
details and CTRL+ALT+ESC fails to break to the debugger as
does and NMI, even though it at least tries printing the
following many times some quite jumbled:-
NMI ... going to debugger

We've configured the dump device but that also seems to fail
to capture any details just sitting there after panic with
Dumping 4465MB:

The machines are single disk ZFS root install and the dump
device is configured using the gptid, could this be what's
preventing the dump happening?

The kernel is compiled with:-
options     KDB         # Kernel debugger related code
options     KDB_TRACE       # Print a stack trace for a panic

We have remove KVM but not remote serial on the most of the
machines.

Any advice on how to debug this issue?

    Regards
    Steve

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