Problem getting savecore to clear old crash dump (2.7-REL)

[Paul Civati <paul_(_at_)_xciv_(_dot_)_org>]

I built a new kernel (unfortunately I no longer have the kernel which
generated the crash dump) so savecore doesn't seem to want to clear
my old crash dump:

# savecore -c
savecore: /bsd: kvm_dump_mkheader: kvm_read: Invalid argument

How do I get around this and clear it manually?

Am I right in thinking the crash dump is stored in the swap partition
somewhere?

[ Aside, the machine would seem to always kernel panic when trying a
reboot, about the time it's syncing the disk:

savecore: reboot after panic: lockmgr: non-release on draining lock: 6

I think I solved this by taking apm out of the kernel. ]

-Paul-