Subject: kern/12547: console break signal ignored
To: None <>
From: None <>
List: netbsd-bugs
Date: 04/04/2001 10:32:31
>Number:         12547
>Category:       kern
>Synopsis:       console break signal ignored if DDB not defined
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Apr 04 08:37:00 PDT 2001
>Originator:     Ron Roskens
>Release:        NetBSD-current 20010401
System: NetBSD 1.5T NetBSD 1.5T (WEBHEAD.MP) #6: Tue Apr 3 14:02:15 CDT 2001 sparc
Architecture: sparc
Machine: sparc
When the cnmagic functionality was added to the kernel, it re-wrote the way
that a kernel could be dropped into the kernel debugger or prom mode.

cn_trap() is called to send you to the debugger, but on systems which don't
define DDB this results in console_debugger() being defined as a NOP
do/while loop. Systems which have a prom mode now cannot reach that mode.

On a sparc ss10, configure a kernel without DDB support. Boot via the resulting
kernel, and send it break signal on the console. Watch it display ^@ instead
of dropping you to the prom mode.