debug on booting

[sudheer linux]

Hi,

I would like to debug while booting freebsd. I tried couple of options but
its not getting into gdb mode while booting.

copied /boot/default/loader.conf to /boot/loader.conf

in /boot/loader.conf, enabled

boot_ddb="-d"
boot_gdb="-g"

If these are not the right options.. rather right way, kindly let me know
how to go about it ?

I basically want to check memory allocation behavior while booting.

Thanks in advance
Sudheer