kern/56262: NVMM aborts doing install of FreeDOS 1.3

[rnestor%mac.com@localhost]

>Number:         56262
>Category:       kern
>Synopsis:       NVMM aborts doing install of FreeDOS 1.3
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jun 18 21:10:00 +0000 2021
>Originator:     Bob Nestor
>Release:        BetBSD-9.1_STABLE
>Organization:
>Environment:
NetBSD netbsd.home.net 9.1_STABLE NetBSD 9.1_STABLE (GENERIC) #0: Mon Jan 25 14:16:00 UTC 2021  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
Playing with FreeDOS 1.2 and 1.3 under nvmm on a NetBSD 9.1-amd64 system and ran into some issues.  Basically I can do an install from the FreeDOS-1.2 CD and run the system afterwards without an issue, but trying to install FreeDOS-1.3 the same way aborts in nvmm.  If the FreeDOS 1.3 install is done on actual hardware it succeeds and the resulting disk image file will boot and run fine under nvmm.  I?ve also tried running an old copy of Norton Symantec Ghost 2003 under both versions (to recover some old files).  It runs fine on real hardware but aborts under nvmm.

Oh, to avoid the system reboot during the installation after FreeDOS partitions and formats the new disk, I do this beforehand using qemu-image create, vndconfig, fdisk, and newfs_msdos.

#
# This works for a FreeDOS 1.2 install
#
qemu-system-x86_64 -accel nvmm -cpu 486 -smp 1 -m 768 -cdrom ./FD12LGCY.iso -netdev tap,id=nd0,ifname=tap0,script=no,downscript=no -device rtl8139,netdev=nd0 -drive file=./FreeDOS-1.2.dsk,media=disk,format=raw

#
# This fails for a FreeDOS 1.3 install
#
qemu-system-x86_64 -accel nvmm -cpu 486 -smp 1 -m 768 -cdrom ./FD13LIVE.iso -netdev tap,id=nd0,ifname=tap0,script=no,downscript=no -device rtl8139,netdev=nd0 -drive file=./FreeDOS-1.3.dsk,media=disk,format=raw
#
# Error displayed when install fails:
#
NetBSD Virtual Machine Monitor accelerator is operational
qemu-system-x86_64: NVMM: Mem Assist Failed [gpa=0xb018f]
qemu-system-x86_64: NVMM: Failed to execute a VCPU.

#
# However, if the FreeDOS 1.3 system is installed using actual hardware
#  the resulting disk image file boots and runs successfully under nvmm.
#

#
# Attemping to run an old copy of Norton Symantec Ghost 2003 in nvmm
#  produces the following error under both FreeDOS 1.2 and FreeDOS 1.3:
# Note: Ghost 2003 runs fine on real hardware on both versions of FreeDOS
#  on systems with 32-bit (i386) or 64-bit (amd64).
#
qemu-system-x86_64: NVMM: Unexpected VM exit code 0xffffffffffffffff [hw=0x9]
qemu-system-x86_64: NVMM: Failed to execute a VCPU.

>How-To-Repeat:
Described above
>Fix:
Unknown, may be a problem in qemu