port-alpha/53327: BREAK on serial console does not enter ddb

[martin%NetBSD.org@localhost]

>Number:         53327
>Category:       port-alpha
>Synopsis:       BREAK on serial console does not enter ddb
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-alpha-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue May 29 12:40:00 +0000 2018
>Originator:     Martin Husemann
>Release:        NetBSD 8.99.19
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD gemini.duskware.de 8.99.19 NetBSD 8.99.19 (GENERIC-$Revision: 1.382 $) #65: Tue May 29 14:11:22 CEST 2018 martin%seven-days-to-the-wolves.aprisoft.de@localhost:/work/src/sys/arch/alpha/compile/GENERIC.MP alpha
Architecture: alpha
Machine: alpha
>Description:

On a machine with serial console and default hw.cn_magic setting (\x27\x01),
sending break on the console doese not invoke ddb any more.

>How-To-Repeat:
s/a

>Fix:
n/a