kgdb on an amd64 kernel anyone?

Hi

Has anyone managed to inspect a vmcore produced by an amd64 kernel
in the last few months?  I've had several crashes, but all the cores
appear corrupted and no useful data can be had.

The latest:

[firewall2.jnb1] /var/crash # kgdb -c vmcore.5 /boot/kernel.old/kernel 
GNU gdb 6.1.1 [FreeBSD]
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "amd64-marcel-freebsd"...(no debugging symbols found)...
Attempt to extract a component of a value that is not a structure pointer.
Attempt to extract a component of a value that is not a structure pointer.
Attempt to extract a component of a value that is not a structure pointer.
Attempt to extract a component of a value that is not a structure pointer.
#0  0x0000000000000000 in ?? ()
(kgdb) bt
#0  0x0000000000000000 in ?? ()
Cannot access memory at address 0x0

Or this followed by pages and pages stack corruption.  The most
frames I've had the patience to scroll through like this is in the
0000s.

[firewall1.jnb1] /var/db/firewall # kgdb -c /var/crash/vmcore.4 /boot/kernel/kernel 
GNU gdb 6.1.1 [FreeBSD]
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "amd64-marcel-freebsd"...(no debugging symbols found)...
Attempt to extract a component of a value that is not a structure pointer.
Attempt to extract a component of a value that is not a structure pointer.
Attempt to extract a component of a value that is not a structure pointer.
Attempt to extract a component of a value that is not a structure pointer.
#0  0xffffffff802bdb8a in doadump ()
(kgdb) bt
#0  0xffffffff802bdb8a in doadump ()
#1  0xffffff81a4af95f0 in ?? ()
#2  0xffffffff802be0bb in boot ()
#3  0xe880695fa0c7c748 in ?? ()
#4  0x9066eaebfff07554 in ?? ()
#5  0x31804b26a0c7c748 in ?? ()
#6  0xc3c900033ee2e8c0 in ?? ()
#7  0x56415741e5894855 in ?? ()
#8  0x48fb895354415541 in ?? ()
#9  0x253c8b486528ec83 in ?? ()
#10 0x000119b900000000 in ?? ()
#11 0x804b26d8c2c74800 in ?? ()
#12 0x65ffff14b1e8f631 in ?? ()
#13 0x00000000253c8b48 in ?? ()
#14 0x65000235f1e8f631 in ?? ()
#15 0x0000000025148b48 in ?? ()
#16 0x450c608b44028b48 in ?? ()
#17 0x000004cd840fe485 in ?? ()
#18 0x00000025348b4865 in ?? ()
#19 0xe80c49ff0e8b4800 in ?? ()
#20 0x68c7c74800148304 in ?? ()
#21 0x05c7df89418048c1 in ?? ()
#22 0x00000001003d81e8 in ?? ()
---Type <return> to continue, or q <return> to quit---q

The last useful crashdump I've had was before February this year.
Do others share this experience?

Ian

--
Ian Freislich