I recently bought an HP CD-RW unit.  When it's hooked up to either of
my SCSI busses, I get strange messages during the boot process:

scsibus0: waiting 2 seconds for devices to settle...
ahc0: target 0 synchronous at 10.0MHz, offset = 0xf
probe(ahc0:0:0): SCB 1d - timed out in Message-in phase, SEQADDR == 0x153
SCSIRATE == 0xf
probe(ahc0:0:0): BDR message in message buffer
probe(ahc0:0:0): SCB 1d - timed out in Message-in phase, SEQADDR == 0x153
SCSIRATE == 0xf
probe(ahc0:0:0): no longer in timeout, status = 0
ahc0: Issued Channel A Bus Reset. 1 SCBs aborted
ahc0: target 6 synchronous at 10.0MHz, offset = 0xf
cd1 at scsibus0 target 6 lun 0: <HP, CD-Writer+ 9200, 1.0e> SCSI4 5/cdrom removable

It causes some delay while booting, but the system seems to function
normally when the boot completes.  Do I need to be concerned about
these messages?  Is there some quirk entry I should be adding for this
drive that will fix whatever is going wrong?

Complete dmesg output follows:

NetBSD 1.5_ALPHA (ZIPPY) #0: Tue Jul 25 23:47:39 EDT 2000
    entropy@zippy.bernstein.com:/usr/src/sys/arch/i386/compile/ZIPPY
cpu0: family 6 model 8 step 1
cpu0: Intel Pentium III (E) (686-class)
total memory = 127 MB
avail memory = 115 MB
using 1658 buffers containing 6632 KB of memory
BIOS32 rev. 0 found at 0xfb130
mainbus0 (root)
pci0 at mainbus0 bus 0: configuration mode 1
pci0: i/o space, memory space enabled
pchb0 at pci0 dev 0 function 0
pchb0: VIA Technologies VT82C691 (Apollo Pro) Host-PCI (rev. 0x42)
ppb0 at pci0 dev 1 function 0: VIA Technologies VT82C598 (Apollo MVP3) PCI-AGP (rev. 0x00)
pci1 at ppb0 bus 1
pci1: i/o space, memory space enabled
vga0 at pci1 dev 0 function 0: 3Dfx Interactive Voodoo3 (rev. 0x01)
wsdisplay0 at vga0: console (80x25, vt100 emulation)
pcib0 at pci0 dev 7 function 0
pcib0: VIA Technologies VT82C596A (Apollo Pro) PCI-ISA Bridge (rev. 0x12)
pciide0 at pci0 dev 7 function 1: VIA Tech VT82C586A IDE Controller (rev. 0x06)
pciide0: bus-master DMA support present
pciide0: primary channel configured to compatibility mode
wd0 at pciide0 channel 0 drive 0: <Maxtor 92041U4>
wd0: drive supports 16-sector pio transfers, lba addressing
wd0: 19541 MB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 40020624 sectors
wd0: 32-bit data port
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 4
pciide0: primary channel interrupting at irq 14
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2 (using DMA data transfers)
pciide0: secondary channel configured to compatibility mode
atapibus0 at pciide0 channel 1
cd0 at atapibus0 drive 0: <ATAPI 44X CDROM, 44XCDROM Ver3.40, VER-3.4> type 5 cdrom removable
cd0: 32-bit data port
cd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 2
pciide0: secondary channel interrupting at irq 15
cd0(pciide0:1:0): using PIO mode 4
uhci0 at pci0 dev 7 function 2: VIA Technologies VT83C572 USB Controller (rev. 0x08)
uhci0: interrupting at irq 11
usb0 at uhci0: USB revision 1.0
uhub0 at usb0
uhub0: VIA Technologie UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
pchb1 at pci0 dev 7 function 3
pchb1: VIA Technologies product 0x3050 (rev. 0x20)
de0 at pci0 dev 8 function 0
de0: interrupting at irq 9
de0: DEC DE450-CA 21041 [10Mb/s] pass 1.1
de0: address 00:00:f8:1e:78:8c
fms0 at pci0 dev 10 function 0: Forte Media FM-801
fms0: interrupting at irq 9
fms0: SigmaTel STAC9704 codec; 18 bit DAC, 18 bit ADC, Rockwell 3D
audio0 at fms0: full duplex, mmap, independent
opl0 at fms0: model OPL3
midi0 at opl0: FMS Yamaha OPL3
mpu0 at fms0
midi1 at mpu0: FM801 MPU-401 MIDI UART
joy0 at pci0 dev 10 function 1: Forte Media product 0x0802 (rev 0xb1)
joy0: joystick not connected
ahc0 at pci0 dev 11 function 0
ahc0: interrupting at irq 9
ahc0: aic7860 Single Channel A, SCSI Id=7, 3/255 SCBs
scsibus0 at ahc0 channel 0: 8 targets, 8 luns per target
ahc1 at pci0 dev 12 function 0
ahc1: interrupting at irq 10
ahc1: aic7850 Single Channel A, SCSI Id=7, 3/255 SCBs
ahc1: Host Adapter Bios disabled.  Using default SCSI device parameters
scsibus1 at ahc1 channel 0: 8 targets, 8 luns per target
isa0 at pcib0
com0 at isa0 port 0x3f8-0x3ff irq 4: ns16550a, working fifo
com1 at isa0 port 0x2f8-0x2ff irq 3: ns16550a, working fifo
pckbc0 at isa0 port 0x60-0x64
pckbd0 at pckbc0 (kbd slot)
pckbc0: using irq 1 for kbd slot
wskbd0 at pckbd0: console keyboard, using wsdisplay0
pmsi0 at pckbc0 (aux slot)
pckbc0: using irq 12 for aux slot
wsmouse0 at pmsi0 mux 0
lpt0 at isa0 port 0x378-0x37b irq 7
pcppi0 at isa0 port 0x61
midi2 at pcppi0: PC speaker
sysbeep0 at pcppi0
isapnp0 at isa0 port 0x279: ISA Plug 'n Play device support
npx0 at isa0 port 0xf0-0xff: using exception 16
fdc0 at isa0 port 0x3f0-0x3f7 irq 6 drq 2
fd0 at fdc0 drive 0: 1.44MB, 80 cyl, 2 head, 18 sec
isapnp0: no ISA Plug 'n Play devices found
biomask ef65 netmask ef65 ttymask ffe7
scsibus0: waiting 2 seconds for devices to settle...
ahc0: target 0 synchronous at 10.0MHz, offset = 0xf
probe(ahc0:0:0): SCB 1d - timed out in Message-in phase, SEQADDR == 0x153
SCSIRATE == 0xf
probe(ahc0:0:0): BDR message in message buffer
probe(ahc0:0:0): SCB 1d - timed out in Message-in phase, SEQADDR == 0x153
SCSIRATE == 0xf
probe(ahc0:0:0): no longer in timeout, status = 0
ahc0: Issued Channel A Bus Reset. 1 SCBs aborted
ahc0: target 6 synchronous at 10.0MHz, offset = 0xf
cd1 at scsibus0 target 6 lun 0: <HP, CD-Writer+ 9200, 1.0e> SCSI4 5/cdrom removable
scsibus1: waiting 2 seconds for devices to settle...
ahc1: target 6 using asynchronous transfers
ss0 at scsibus1 target 6 lun 0: <, scanner 636EL, 1.40> SCSI2 6/scanner fixed
boot device: wd0
root on wd0a dumps on wd0b
root file system type: ffs
XFree86 aperture driver version 1.99b
Pentium Pro MTRR support enabled
de0: enabling BNC port
wsdisplay0: screen 1 added (80x25, vt100 emulation)
wsdisplay0: screen 2 added (80x25, vt100 emulation)
wsdisplay0: screen 3 added (80x25, vt100 emulation)
wsdisplay0: screen 4 added (80x25, vt100 emulation)
wsmux1: connecting to wsdisplay0

--
entropy -- it's not just a good idea, it's the second law.