The bsdcrashtar utility creates tar a archive that contains all files needed
for debugging FreeBSD kernel crash (vmcore, kernel, loaded modules, sources
that appear in backtrace). This is useful for debugging a crash on another
host, sending it to developers or if you are going to upgrade the kernel on
crashed host but would like to keep crashdump in case the developers ask you to
provide additional info.

Created tar archive contains also a script that when being run inside unpacked
archive will give kgdb(1) session with crash core loaded in it. The script
should be run with root privileges because it does chroot(8) before starting
kgdb(1).