kern/38937: aprint_debug calls make no sense during shutdown

[martin%duskware.de@localhost]

>Number:         38937
>Category:       kern
>Synopsis:       aprint_debug calls make no sense during shutdown
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jun 10 20:30:00 +0000 2008
>Originator:     Martin Husemann
>Release:        NetBSD 4.99.64
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD night-porter.duskware.de 4.99.64 NetBSD 4.99.64 (PORTER) #50: 
Tue Jun 10 18:56:22 CEST 2008 
martin%night-porter.duskware.de@localhost:/usr/src/sys/arch/i386/compile/PORTER 
i386
Architecture: i386
Machine: i386
>Description:

While trying to debug a shutdown issue, I wonderd why the tons of aprint_debug
messages that should be issued by pmf_system_shutdown() and the functions
it calls never showed up.

I'll leave out the long confusion untill I noticed the obvious: cpu_reboot()
overwrites boothowto, so at that moment aprint_debug and aprint_verbose
stop to work.

>How-To-Repeat:

boot -svxd
at the db prompt: x boothowto; break pmf_system_shutdown; c
at tha shell prompt: halt -p
at the db prompt: x boothowto

>Fix:
copy flags to controll aprint_* early at bootup to a separate variable and
have the actual aprint_*_internal functions test that instead?