bin/54201: disklabel(8) annoyingly overrides user intent when run as a "native" tool

[thorpej%me.com@localhost]

>Number:         54201
>Category:       bin
>Synopsis:       disklabel(8) annoyingly overrides user intent when run as a "native" tool
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun May 12 23:20:00 +0000 2019
>Originator:     Jason Thorpe
>Release:        8.99.37
>Organization:
Jason's messy garage of hackery
>Environment:
NetBSD netbsd-vm 8.99.37 NetBSD 8.99.37 (GENERIC) #19: Mon Apr 15 08:49:13 PDT 2019  thorpej@BigMac.local:/Volumes/Data0/Users/thorpej/hack/NetBSD/current/netbsd-src/sys/arch/amd64/compile/GENERIC amd64

>Description:
The -m flag for disklabel(8) behaves differently when build as a host tool vs run as a native tool with a different target machine.  In my scenario, I was attempting to write a disklabel to a NetBSD MBR partition for evbmips.  This failed when run as a "native" tool with -M evbmips on NetBSD/amd64, but succeeded when the host tool (nbdisklabel) was run with the same arguments.

The handling of the -m flag seems unnecessarily complex in the disklabel(8) code, and also seems that how it works to lead to user confusion.
>How-To-Repeat:
Use disklabel -m as a "native" tool with a different target machine that does not normally "use mbr".
>Fix:
Unknown.