install/47671: How do I manually add an extra MBR style disk?

[andrew.cagney%gmail.com@localhost]

>Number:         47671
>Category:       install
>Synopsis:       How do I manually add an extra MBR style disk?
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    install-manager
>State:          open
>Class:          doc-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 20 01:35:00 +0000 2013
>Originator:     cagney
>Release:        trunk
>Organization:
>Environment:
NetBSD rpi 6.99.17 NetBSD 6.99.17 (RPI) #3: Fri Mar 15 16:35:21 EDT 2013  
cagney@tv-desktop:/home/cagney/src/NetBSD/cvs/sys/arch/evbarm/compile/obj/RPI 
evbarm

>Description:
This is idle speculation, but I suspect the sequence is meant to be something 
like:

-- resize dos partition using another operating system
# fdisk -u /dev/rsd0
-- adjust things to add a netbsd partition
mprlabel -w /dev/rsd0
-- kind of gets it right
disklabel -i /dev/rsd0
-- first move things round so that c is the above partition and d is the entire 
disk, and then add a, b, h, ...

except I can't find anything in "The Manual" to confirm this.

I also noticed:

- disklabel has the comment:

<<
On systems that expect to have disks with MBR partitions (see fdisk(8))
disklabel will find, and update if requested, labels in the first 8k of
type 169 (NetBSD) MBR labels and within the first 8k of the physical
disk.
>>

is this still true, or has this been supplanted by mbrlabel?  If it is true, it 
doesn't work reliably.

It continues:

<<
On other systems disklabel will only look at the start of the
disk.
>>

Is this true, or should it spot the MBR and act like i386 et.al.

<<
The offset at which the labels are written is also system
dependent.
>>

is this true when there's an MBR?

-- mbrlabel (assuming I'm meant to be using it)

It doesn't seem to let me specify which partitions should get which letters (a 
ended up being dos), or that it should start from scratch?
>How-To-Repeat:
Try to add a disk with an existing MBR partition table.
>Fix: