>   That error message comes from a strange condition seen by the NetBSD
> driver as well as the Mach driver (from which the NetBSD driver was
> derived).  The drive appears to done a disconnect, has reconnected, and
> the DMA transfer restarted.  Then a "bus service" interrupt occurs, but
> the DMA transfer is still in progress and appears to be functioning
> normally.

OK, sounds like a timing thing.  Is there a counter or something to twiddle
to buy just a little time before the interrupt gets set?  It would seem
that something needs to make sure that if the DMA transfer is important
enough to require completion at that point, the other interrupts should
not be allowed to occur until the transfer is done.  I am curious as to
what bit in the code it is?

> ......... If I remember correctly, the 'tc' value is the remaining byte
> count of the DMA transfer, and will vary depending on how far the transfer
> has gotten by the time the interrupt occurs and what the original transfer
> request size was.  The Mach driver was just noting the interrupt and
> 'ignores' it.  The NetBSD driver also just notes the interrupt occurred
> and continues.

I get tc values in the range of 600-1800? if I am remembering the values
correctly, and they seem to occur mostly in the 900-1000 range.

If it is just a service message, with no particular faults, then do we
need that in the code at that point?  Would a comment that such interrupt
spuriousness occurs, but is not doing any damage, and then also to ignore
it as was originally done, be appropriate?

I am curious as to on which different machines this particular spurious
interrpt ignored message occurs?

Just thinking out loud again.....

Bob