Help needed with BBN 4.1 Ethernet UBA IVMR errors

[chris at umcp-cs.UUCP]

We've been getting some odd UBA IVMR errors on our InterLAN Ethernet
board (which is being run by the BBN 4.1BSD network code, sys 10)
which are driving me up the wall.  I put traps in ubaremap (which
is all that's ever used in il.c, after the initial allocation) to
panic on invalid remaps (in fact, we found one bug that way), and
it claims that the pages that are being assigned to the map registers
are valid and kernel-writable, yet we still see the IVMR errors.

Harware problem?  Known 780 UBA bug?  Or what?  Ideas would be most
appreciated.

Thanks in advance (maybe I should postdate them?),
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci (301) 454-7690
UUCP:	{seismo,allegra,brl-bmd}!umcp-cs!chris
CSNet:	chris at umcp-cs		ARPA:	chris at maryland