```
# sysctl debug.kdb.enter=1
debug.kdKDB: enter: sysctl debug.kdb.enter
[ thread pid 1062 tid 100202 ]
Stopped at kdb_sysctl_enter+0x84: sd zero,0(s1)
db> bt
Tracing pid 1062 tid 100202 td 0xffffffc2085805a0
kdb_sysctl_enter() at kdb_sysctl_enter+0x82
sysctl_root_handler_locked() at sysctl_root_handler_locked+0xaa
sysctl_root() at sysctl_root+0x1ea
userland_sysctl() at userland_sysctl+0x124
sys___sysctl() at sys___sysctl+0x56
do_trap_user() at do_trap_user+0x200
cpu_exception_handler_user() at cpu_exception_handler_user+0x72
--- syscall (202, FreeBSD ELF64, sys___sysctl)
db>
```