It happens always :)

trap: kernel read DSI trap @ 0x55500c by 0x37b7f0 (DSISR 0x40000000, err=14)
panic: trap
Stopped at	netbsd.cpu_Debugger+0x10:	lwz	r0, r1, 0x14
db> bt

0x006a1c60:	at panic+0x19c
0x006a1cf0:	at trap+0xfc
0x006a1d70:	kernel DSI read trap @ 0x5555000c by m_xhalf+0x4c: 		 	
srr1=0x9032 r1=0x6a1e30 cr=0x40209032 xer=0x20000000  		 		ctr=0x37ba30
dsisr=0x40000000
0x006a1e30:	at ADBDevTable+0xf078a08
0x006a1e40:	at _bus_dmamap_load_buffer+0x1e8
0x006a1ec0:	at bpf_mtap+0xcc
0x006a1ef0:	at gem_rint+0x4c4
0x006a1f40:	at gem_intr+0x128
0x006a1f70:	at ext_intr_openpic+0x178
0x006a1fa0:	at trapstart+0x91c
0xd5539e60:	at Idle+0x24
0xd5539e70:	at mi_switch+0x198
0xd5539ea0:	at ltsleep+0x41c
0xd5539ee0:	at sched_sync+0x184
0xd5539f40:	at cpu_switchto+0x44
0xd5539f50:	at ADBDevTable+0x2c22ca08

It's an iBook G4 14" 1.33Ghz
Same thing happened on -current some time ago.
regards,
-- 
Bartek Krawczyk
GG: 2094683
JID: bkrawczyk@jabberpl.org