port-sh3/55826: Serial console on landisk doesn't work in single user mode

[john%ziaspace.com@localhost]

>Number:         55826
>Category:       port-sh3
>Synopsis:       Serial console on Landisk doesn't work in single user mode
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    port-sh3-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Nov 26 16:45:00 +0000 2020
>Originator:     John Klos
>Release:        NetBSD 9.1_STABLE
>Organization:
	
>Environment:
	
	
System: NetBSD amanda.zia.io 9.1_STABLE NetBSD 9.1_STABLE (GENERIC) #0: Wed Nov 25 21:35:58 UTC 2020 john%frigg.zia.io@localhost:/usr/obj-landisk/sys/arch/landisk/compile/GENERIC landisk
Architecture: sh3el
Machine: landisk
>Description:
	
When booting NetBSD 9.1 on landisk (Plextor) in single user mode, no console appears:

[   2.3903491] boot device: wd0
[   2.4216506] root on wd0a dumps on wd0b
(nothing - no response)

The serial console works when multi-user and in the boot menu, but not in single user.
The power button works, though:

[  37.3121311] pwrsw0: power button pressed, shutting down!
[  37.3683361] syncing disks... done
[  37.4081005] unmounting file systems...
[  37.4530922] unmounting done

>How-To-Repeat:
	
>Fix:
	

>Unformatted: