I found my PR ticket; it's kern/25710.

http://www.netbsd.org/cgi-bin/query-pr-single.pl?number=25710

Just to echo what John has said,

> > Thanks John. For your Promise card problem, have a look at (you
> > probably have already, just in case):
> > http://www.promise.com/support/faq/faq_answer_eng.asp?faq_id=292
> 
> No, it's not the cable or the drive. I have proper cables and all sorts of 
> modern drives. Nor is it that the drive negotiates to 33 MB/sec at boot; 
> it negotiates at 100 MB/sec or 133 MB/sec, then, after the very first 
> attempt to communicate with the drive, the kernel reports a CRC error and 
> switches to 33 MB/sec mode.

... exactly what I've observed. The drive is an ATA/100, and it's legitimately
detected as such, but as soon as the filesystem comes up,

pciide0 at pci1 dev 2 function 0: Promise Ultra133/ATA Bus Master IDE Accelerator (rev. 0x02)
pciide0: bus-master DMA support present
pciide0: primary channel configured to native-PCI mode
pciide0: using irq 25 for native-PCI interrupt
wd0 at pciide0 channel 0 drive 0: <WDC WD400JB-00ENA0>
wd0: drive supports 16-sector PIO transfers, LBA addressing
wd0: 38166 MB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 78165360 sectors
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 5 (Ultra/100)
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 5 (Ultra/100) (using DMA data transfers)
pciide0: secondary channel configured to native-PCI mode
:
:
wd0: transfer error, downgrading to Ultra-DMA mode 2
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2 (Ultra/33) (using DMA data transfers)
wd0c: error reading fsbn 0 (wd0 bn 0; cn 0 tn 0 sn 0), retrying
wd0: (aborted command, interface CRC error)
wd0: soft error (corrected)

Exceptionally irritating.

The earlier problem I had with frequent fsbn errors turned out to be a bad
power supply connection. However, switching power supplies, cables, whatever,
has not fixed this for me either.

-- 
---------------------------------- personal: http://www.armory.com/~spectre/ --
 Cameron Kaiser, Floodgap Systems Ltd * So. Calif., USA * ckaiser@floodgap.com
-- Stand by to launch beef by-product into oscillating ventilation unit ... ---