port-i386/53984: i386 hangs at boot since Hyper-V commit

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         53984
>Category:       port-i386
>Synopsis:       i386 hangs at boot since Hyper-V commit
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    port-i386-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Feb 15 20:10:00 +0000 2019
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date >= 2019.02.15.08.54.02
>Organization:

>Environment:
System: NetBSD
Architecture: i386
Machine: i386
>Description:


Since the commit adding Hyper-V support on 2019.02.15.08.54.02, the
i386 tests on the TNF testbed are hanging when booting the INSTALL
kernel, after printing the line

  [   1.0358810] acpicpu0 at cpu0: ACPI CPU

Logs at:

  http://releng.netbsd.org/b5reports/i386/commits-2019.02.html#2019.02.15.08.54.02

>How-To-Repeat:

>Fix: