On Tue, 20 May 1997, Bertram Barth wrote:

> Oscar Oberg writes:
> [...]
> > b) I'm getting SCSI (I assume) errors of this kind:
> > 
> > DMA incomplete: ntrans=8193/16384, lock=98
> > si_dma_stop: timeout?
> [...]                                                           
> > Is this a software or hardware problem? I've recently installed a SCSI1
> > CDROM, and I don't recall getting any of these errors before I did. If
> > it's a problem w/ the CDROM, what could it be?

> This is a software/driver problem. There are some real bugs/problems
> in the NCR driver. One of them is that transfers get interrupted for
...
> Because of these problems there's a "work-around" (ie. ugly hack) in 
> the scsi-driver which busy-waits for some time after starting a transfer,
> so that the transfer won't be interrupted. The wait-time is "calculated" 
> out of the transfer size and some "don't-ask-me" constant. Since I 
> "found" this constant on my VS2000 with one SCSI-disk, I assume that
...

Hmmmmm... Just a quick sanity check on my part.  I was under the
impression that the VAXstation 2000s didn't have SCSI support apart from
the not-quite SCSI support for a VS2000 specific TK50.  Is my thinking
incorrect?  Do VAXstation 2000s actually have full SCSI support?

> Anyways, the NCR/SCSI driver should be rewritten since these bloody
> busy-waits slow down disk operations a lot. I hope I'll have some
> spare time in june so that I can do that. Let's hope that these
> problems disappear with a new driver.

> PS: If anybody else is interested in (re-)writing the SCSI driver,
>     I would not mind...   ;-)


Bertam,
I've never written a device driver before (just tweaked existing ones),
but if you point me to the NetBSD/VAX source with your support of the
VAXstation 3100 I'd be more than happy to make an attempt at the SCSI
driver for that machine. Even if just for the sake of learning more about
NetBSD, (or perhaps just to keep myself humble.)

-brian.
---------------------------------------------------------------------------
Brian D. Chase         Systems Coordinator        brian.chase@carpediem.com
-- Compression, Inc. - 13765 Alton Pkwy, Suite B - Irvine, CA 92618, USA --