I just built a kernel with every wee bit of debug enabled that I could find.
Should I futz with load-base?  (as I recall to myself some gory days with
MacPPCs)

...
13000 >> NetBSD/sparc64 OpenFirmware Boot, Revision 1.7
>> (peter@zipper, Tue Jun  1 12:10:45 CDT 2004)
bootp: no reply
Using BOOTPARAMS protocol: ip address: 12.30.65.29, hostname: e450
root addr=12.30.65.28 path=/export/e450/root
main: Calling loadfile(fd, /pci@1f,4000/network@1,1/netbsd -d)
loadfile: reading header
elf64_exec: Booting /pci@1f,4000/network@1,1/netbsd
4350792@0x1000000+159456@0x1800000+4034848@0x1826ee0
symbols @ 0xfef7a440 164+309672+188731 start=0x1000000
chain: calling OF_chain(800000, cbb8, 1000000, fff7fa80, 18)
Type  'go' to resume
{0} ok go
OF_chain: prom returned!
Calling entry(0, 0xfff7fa80, 18, f0075a4c, f0075a4c)
Loaded initial symtab at 0xfef7a000, strtab at 0xfefc5e90, # entries 12889
Entered pmap_bootstrap.
Available virtual memory:
memlist start 0xfffff80000000000 size 7fc00000000
memlist start 0x100000000 size 7ff00000000
memlist start 0xffff0000 size e000
memlist start 0x1c00000 size ee400000
memlist start 0x1428000 size 3d8000
memlist start 0x0 size 1000000
memlist start 0xfff1a000 size 2000
memlist start 0xfff0e000 size 4000
memlist start 0xfef00000 size 7a000
memlist start 0xf0800000 size e6f4000
End of available virtual memory
Trying to allocate msgbuf at e0006000, size 8000
Fast Data Access MMU Miss
{0} ok 


{0} ok printenv
Variable Name         Value                          Default Value

tpe-link-test?        true                           true
scsi-initiator-id     7                              7
keyboard-click?       false                          false
keymap             
ttyb-rts-dtr-off      false                          false
ttyb-ignore-cd        true                           true
ttya-rts-dtr-off      false                          false
ttya-ignore-cd        true                           true
ttyb-mode             9600,8,n,1,-                   9600,8,n,1,-
ttya-mode             9600,8,n,1,-                   9600,8,n,1,-
pci-slot-skip-list    none                           none
pci0-probe-list       1,3,2,4                        1,3,2,4
upa-port-skip-list    none                           none
memory-interleave     auto                           auto
disk-led-assoc        0                              0
diag-level            min                            min
diag-script           normal                         normal
diag-targets          none                           none
diag-trigger          power-reset                    power-reset
diag-continue?        false                          false
diag-passes           1                              1
diag-verbosity        tests                          tests
env-monitor           enabled                        enabled
mfg-options           server
#power-cycles         54
system-board-serial#  007H34DF
system-board-date     38a50536
fcode-debug?          true                           false
output-device         screen                         screen
input-device          keyboard                       keyboard
load-base             16384                          16384
boot-command          boot                           boot
auto-boot?            true                           true
auto-boot-on-error?   false                          false
watchdog-reboot?      true                           false
diag-file          
diag-device           net                            net
boot-file          
boot-device           net                            disk net
local-mac-address?    false                          false
ansi-terminal?        true                           true
screen-#columns       80                             80
screen-#rows          34                             34
silent-mode?          false                          false
use-nvramrc?          false                          false
nvramrc            
security-mode         none
security-password  
security-#badlogins   4096
oem-logo           
oem-logo?             false                          false
oem-banner         
oem-banner?           false                          false
hardware-revision     UUUUUUUU ...
last-hardware-update
diag-switch?          false                          false
{0} ok