dell poweredge 1850 and interrupt re-mapping (disks timeout)

[john refling <netbsdrat%gmail.com@localhost>]

I have a Dell poweredge 1850 and have tried installing adaptec 29160 /
39160 scsi cards.

The scsi devices always time out.  A freebsd post a few years ago points to
the same problem I have on NetBSD 5.1:

*ahc1: Timedout SCB already complete. Interrupts** may not be functioning.
***
here:
http://lists.freebsd.org/pipermail/freebsd-scsi/2003-September/000566.html

I assume that this is a similar issue, namely with the Dell BIOS being
broken and reporting interrupts incorrectly, and then kernel not getting
correct interrupt.

In the FreeBSD thread there was a post detailing how to turn the re-mapping
off in the kernel:

http://lists.freebsd.org/pipermail/freebsd-scsi/2003-September/000568.html

Is there a way to do so in the NetBSD kernel?  I looked around and couldn't
find a similar code in the NetBSD pci.c.  (Of course the code is several
years apart).

OR, is there a way to hard code the interrupt for the ahc into the kernel?

By the way, a Maxtor basic IDE controller has the same problem.  The disks
always timeout.  I suspect same interrupt problem.

Both of these controllers work correctly with NetBSD on other Dell
computers, just not the poweredge.

I'm running NetBSD 5.1 i386 release.  I looked thru the ahc.c code in
-current and didn't see too many significant changes, but possible this was
fixed elsewhere.

Help appreciated,

john
refling