Porting DVMA Driver to Sun OS 4.0.3

[David B Stewart]

I ported a driver using the Sun DVMA from Sun OS 3.x to Sun OS 4.0.3, on a
Sun 3/160.  Everything works well until I try to interrupt a program which
is using the DVMA, such as typing ^C to break out of the program.

At that time, the Sun crashes, offering the following error messages from
the kernel:

>Oct 18 01:07:57 helios vmunix: assertion failed: pmg->pmg_keepcnt == 1, file: ../../sun/vm_hat.c, line: 1574
>Oct 18 01:07:57 helios vmunix: panic: assertion failed
>Oct 18 01:07:57 helios vmunix: syncing file systems... [9] [9] [7] [4] done

I don't have the source code, so I can't even look at line 1574 to get an
idea of what the problem is.

I would appreciate any clues to the meaning of this error message, and
possible ways to correct it.

David B. Stewart, Dept. of Electrical and Computer Engineering,
		and The Robotics Institute, Carnegie Mellon University
email: stewart at faraday.ece.cmu.edu, office: 412-268-7120; lab: 412-268-3652.