Sun 4/370 with Ironics VME board problem

[Mark Zischke]

Configuration: Sun 4/370 running SunOS 4.1.1, 56MB memory

In our Sun 4/370 we have an Ironics MCPL (Multi Crate Pipeline) board
installed which we plan to use for fast (10+MB/sec) data transfers between
the Sun and another VME chassis (the MCPL board is *not* a VME repeater).
We are unable to use the MCPL because it consistently and immediately
crashes our Sun.

The problem seems to be specific to Sun 4's, since Ironics currently uses
Sun 3's for development and cannot reproduce this problem on their
equipment.

The problem has been traced to a timing problem in the Sun where it
doesn't assert DTACK* soon enough.  Since the MCPL board releases the VME
bus after the Sun asserts DTACK*, the Sun's watchdog timer in turn times
out the MCPL board and the crash happens.

Sun also told us that this problem is *not* specific to the MCPL board; at
least one other group using a board that does a lot of VME traffic (a
board that does FFTs) has run across this problem.

Sun has sent us a patch which we have installed and tested.  However, the
patch only lets the test run a second or so longer before crashing.  We
still do not have a way to transfer large amounts of data quickly from a
VME chassis to the Sun.

Is anyone in a similar situation and does anyone have any ideas?

Thanks for your help!

Mark Zischke
zischke at trwacs.fp.trw.com or uunet!trwacs!zischke
Telephone: 703.876.4260