--- baseline, stock kernel ---
$ kldload /tmp/globalsym.ko; echo GLOBALSYM_RC=$?
GLOBALSYM_RC=0
$ kldstat | tail -3
 2    1 0xffffffff81cd9000    7c2888 ehci.ko
 3    1 0xffffffff81d56000    8c778 xhci.ko
 4    1 0xfffff80116944000     1000 globalsym.ko
$ kldunload /tmp/globalsym.ko; echo UNLOAD_RC=$?
UNLOAD_RC=0

$ kldload /tmp/localsym.ko; echo LOCALSYM_RC=$?
kldload: an error occurred while loading module /tmp/localsym.ko. Please check dmesg(8) for more details.
LOCALSYM_RC=1
$ vm.sh log 8 (serial console)
login: link_elf: symbol s undefined