The following reply was made to PR port-vax/26138; it has been noted by GNATS.

From: Kirk Russell <kirk@ba23.org>
To: gnats-bugs@NetBSD.org
Cc: port-vax-maintainer@NetBSD.org, <kirk.russell@acm.org>
Subject: Re: port-vax/26138
Date: Sun, 1 Oct 2006 11:12:45 -0400 (EDT)

 I think the fix to mscp_disk.c is part of the solution -- because this
 fix appear to work okay with NetBSD 1.6.X.  But it doesn't appear
 to be enough because I can still get most/all future releases of
 the kernel to panic/crash when using an MSCP floppy diskette.
 In other words, there are still more MSCP floppy driver regressions
 somewhere in mscp_disk.c and this issue is not resolved yet.
 
 Here is a panic using simh and NetBSD 4.0_BETA.
 
 VAX simulator V3.6-0
 
 KA655-B V5.3, VMB 2.7
 Performing normal system tests.
 40..39..38..37..36..35..34..33..32..31..30..29..28..27..26..25..
 24..23..22..21..20..19..18..17..16..15..14..13..12..11..10..09..
 08..07..06..05..04..03..
 Tests completed.
 >>>boot dua2
 [...]
 M2529420+73964=0x27bc04
 MCopyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
     The NetBSD Foundation, Inc.  All rights reserved.
 Copyright (c) 1982, 1986, 1989, 1991, 1993
     The Regents of the University of California.  All rights reserved.
 
 NetBSD 4.0_BETA (INSTALL) #0: Tue Sep  5 01:20:29 EDT 2006
     kirk@greyhawk:/bstg/netbsd-4/vax/obj/sys/arch/vax/compile/INSTALL
 MicroVAX 3800/3900
 cpu: KA655, CVAX microcode rev 6 Firmware rev 83
 total memory = 32708 KB
 avail memory = 28872 KB
 mainbus0 (root)
 ibus0 at mainbus0
 uba0 at ibus0: Q22
 dz1 at uba0 csr 160100 vec 304 ipl 15
 uda0 at uba0 csr 172150 vec 774 ipl 15
 mscpbus0 at uda0: version 3 model 3
 mscpbus0: DMA burst size set to 4
 ra0 at mscpbus0 drive 0: RA92
 ra1 at mscpbus0 drive 1: RA92
 ra2 at mscpbus0 drive 2: RRD40
 rx0 at mscpbus0 drive 3: RX50
 md0: internal 1536 KB image area
 boot device: ra2
 root on md0a dumps on md0b
 root file system type: ffs
 Clock has gained 25 days - CHECK AND RESET THE DATE.
 [...]
 # dd if=/dev/rx0a of=/dev/null
 panic: Segv in kernel mode: pc 800a8432 addr d8