This bug is a real hurdle for KDE on kfreebsd-* as it enforces a manual X restart by the user at every reboot. (Rising the kdmrc ServerTimeout as mentioned in various places doesn't help either). kFreeBSD porters: could you please take a look at that ?
When the start of kdm is not during boot, it works fine.
The problem is order of start during boot.
The /etc/inittab line
l2:2:wait:/etc/init.d/rc 2
is performed before
2:23:respawn:/sbin/getty 38400 ttyv1 cons25
therefore during kdm/X start, the vt2 (ttyv1, ALT+F2) is still free.
When started after boot, the vt2 is occupied
and vt7 (ttyv6, ALT+F7) is allocated correctly.
The easiest solution for now is to alter ServerArgsLocal
at least on GNU/kFreeBSD in /etc/kde4/kdm/kdmrc to
"ServerArgsLocal=vt7 -br -nolisten tcp"
Xdm uses on both GNU/Linux and GNU/kFreeBSD in /etc/X11/xdm/Xservers
":0 local /usr/bin/X :0 vt7 -nolisten tcp"
Petr