toolchain/56302: gdb does not work on mipsn64

[martin%NetBSD.org@localhost]

>Number:         56302
>Category:       toolchain
>Synopsis:       gdb does not work on mipsn64
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Jul 11 10:00:01 +0000 2021
>Originator:     Martin Husemann
>Release:        NetBSD 9.99.86
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD supremacy.duskware.de 9.99.86 NetBSD 9.99.86 (OCTEON) #5: Tue Jul 6 16:21:35 CEST 2021 martin%seven-days-to-the-wolves.aprisoft.de@localhost:/work/src/sys/arch/evbmips/compile/OCTEON evbmips
Architecture: mipsn64eb
Machine: evbmips
>Description:

Something is wrong with gdb on mipsn64eb - any non trivial action causes:

(gdb) n
Register 0 is not available
(gdb) 


>How-To-Repeat:

Start a program with a breakpoint set, hit the breakpoint, try to step.

>Fix:
n/a