HP 715/50 NetBSD 4.99.26 deadlock at boot detected

In order to find out why NetBSD hangs I booted the GENERIC kernel with DEBUG and DIAGNOSTIC options enabled. 
The system halts almost immediately early in the booting. No clues what to do with this ....
Your comments are welcome

BTW I checked the machine and both scsi drives, battery, RAM and the rest is in good condition so this is not a sympton of a hardware failure 
If this is not obvious, I used serial line to attach to the machine (not even sure if hill stuff works at all and I have only one hp-hil keyboard 
which is a real precious thing these days)

The version of NetBSD I am writing about in all the three messages is a crosscompilation of 4.99.26 (make release) on a
i386 NetBSD 4.20.  
-------------------------------------------------------------------------------

              (c) Copyright Hewlett-Packard Company, 1991, 1992
Portions of this code are (c) Copyright Samsung Electronics Co., Ltd, 91, 92 

PDC ROM rev. 1.3
IODC ROM rev. 1.1
256 MB of memory have been configured.

Selecting a system to boot.
To stop selection process, press and hold the ESCAPE key.

Booting from:     scsi.1.0     COMPAQ  ST32550N

Hard booted.

NetBSD/hp700 FFS/LFS Primary Bootstrap

32bit firmware

booting from partition a
filesystem: FFS
looking up boot.hp700
looking up boot
loading boot at 0x22800...done

>> NetBSD/hp700 LIF/FFS/LFS Boot, Revision 1.3
>> (n4@small, Sun Jun 24 23:04:08 CEST 2007)
>> Enter "reset" to reset system.
Boot: [[[dk1a:]netbsd][-a][-c][-d][-s][-v][-q]] :- netbsd.d -v
10579492+110592+479232 [320672+284621]=0xd2403c
Start @ 0x200000 [1=0xe90000-0xf2403c]...
PDC_CACHE_SETCS: 0, 0, 0, 0 (-2)
SPID bits: 0x0, error = -2
btlb info: minsz=128, maxsz=16384
btlb fixed: i=0, d=0, c=16
btlb varbl: i=0, d=0, c=0
WARNING: PDC_TLB_INFO failed: -1, using HPT size 4096
HP9000/715/50 (Scorpio), PA7100
  [ BTLB slot 0: r-x--- 0x00200000 @ 0x0:0x00200000 len 0x00200000 ]  
  [ BTLB slot 1: r-x--- 0x00400000 @ 0x0:0x00400000 len 0x00400000 ]  
  [ BTLB slot 2: r-x--- 0x00800000 @ 0x0:0x00800000 len 0x00400000 ]  
  [ BTLB slot 3: r-x--- 0x00c00000 @ 0x0:0x00c00000 len 0x00200000 ]  
  [ BTLB slot 4: rw---- 0x00e00000 @ 0x0:0x00e00000 len 0x00200000 ]  
  [ BTLB slot 5: rw---- 0x01000000 @ 0x0:0x01000000 len 0x01000000 ]  
WARNING: HPT init error -1
pdc_coproc: 0xc0, 0xc0
Loaded initial symtab at 0xe90000, strtab at 0xede86c, # entries 20023
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 4.99.26 (GENERICD) #0: Sun Aug  5 19:55:10 CEST 2007
	n4@small:/n4/usr/obj.hppa/sys/arch/hp700/compile/GENERICD
HP9000/715/50 (Scorpio)
real mem = 256 MB (73728 reserved for PROM, 232 MB used by NetBSD)
avail mem = 228 MB
timecounter: Timecounters tick every 10.000 msec
mainbus0 (root)Mutex error: mutex_vector_enter: locking against myself

lock address : 0x0000000000e6e24c
current cpu  :                  0
current lwp  : 0x0000000000e89c60
owner field  : 0x00000000ffffff10 wait/spin:                0/1

panic: lock error
Stopped in pid 0.1 (system) at  netbsd:cpu_Debugger+0x10:       ldo     R'40(%r3),%r30
db> c
syncing disks... done
pwr_sw_control=0 enable=0
rebooting...