kern/57569: ddb(4) should have a command to print stack traces for all CPUs

[campbell+netbsd%mumble.net@localhost]

>Number:         57569
>Category:       kern
>Synopsis:       ddb(4) should have a command to print stack traces for all CPUs
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Aug 05 14:45:00 +0000 2023
>Originator:     Taylor R Campbell
>Release:        current
>Organization:
The NetBStopped in pid 1497.273 (firefox) at    netbsd:breakpoint+0x5:  leave
>Environment:
having its hottest summer in history
>Description:
The trace (bt) command in ddb should have a way to print a stack trace for every CPU in the system, for diagnosis when something is wedged in, e.g., an interrupt handler or at high IPL with the kernel lock held.
>How-To-Repeat:
1. Put an infinite loop in a secretly chosen interrupt handler.
2. Try to find which interrupt handler it was when the system wedges.
>Fix:
Yes, please!