learning freebsd kernel

[gahn]

hi gurus:

how could i create the core dumps on freebsd kernel? i am trying to create a kernel core dump on 8.1 but it didn't happen:

# sysctl -w debug.kdb.panic=1

well the system went panic, entered the mode db>. i did "reboot' but there was no core/kernel dumps under /var/crash.

the customized kernel has those information enabled:

# Debugging for use in -current
options         KDB                     # Enable kernel debugger support.
options         DDB                     # Support DDB.
options         GDB                     # Support remote GDB.

user at host:~:$ sysctl -a | grep debug.kdb
debug.kdb.stop_cpus: 1
debug.kdb.trap_code: 0
debug.kdb.trap: 0
debug.kdb.panic: 0
debug.kdb.enter: 0
debug.kdb.current: ddb
debug.kdb.available: ddb 



by the way, where is my gdb? on one of my company's machisne, it looks like this:

debug.kdb.available: ddb gdb

thank you all

/gahn