install/56884: Starting NetBSD-9.99 in a VirtualBox with 4 CPUs hangs at startup

[roland.illig%gmx.de@localhost]

>Number:         56884
>Category:       install
>Synopsis:       Starting NetBSD-9.99 in a VirtualBox with 4 CPUs hangs at startup
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    install-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jun 14 21:05:00 +0000 2022
>Originator:     Roland Illig
>Release:        9.99.97
>Organization:
>Environment:
NetBSD nbinst.fritz.box 9.99.97 NetBSD 9.99.97 (GENERIC) #0: Mon Jun 13 20:16:53 UTC 2022  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
Install NetBSD in a VirtualBox VM, using the default settings.
I am using VirtualBox 6.1.34r150636 on Windows.
Shut down the VM.
In VirtualBox, change the CPUs from 1 to 4.
Start the VM.

The screen shows 4 lines:
acpicpu0 at cpu0: ACPI CPU
acpicpu1 at cpu1: ACPI CPU
acpicpu2 at cpu2: ACPI CPU
acpicpu3 at cpu3: ACPI CPU

After that, there is no further progress, all 4 CPUs are busy.
Typing some keys doesn't show anything on the screen.
Pressing Num Lock, Caps Lock or Scroll Lock toggles the keyboard LEDs.

Killing the VM and then starting it with a single CPU works flawlessly.
>How-To-Repeat:

>Fix: