Re: BSD disklabel partition letters in NetBSD

[Don NetBSD <netbsd-embedded%gmx.com@localhost>]

On 9/27/2018 3:41 AM, Rocky Hotas wrote:
> > Sent: Tuesday, September 25, 2018 at 11:51 PM
> > From: "Don NetBSD" <netbsd-embedded%gmx.com@localhost>
> > To: netbsd-users%netbsd.org@localhost
> > Subject: Re: BSD disklabel partition letters in NetBSD
>
> [...]
>
> > But it isn't placed in any of these places unless/until the system is
> > DIRECTED to do so.  I.e., you can access a brand-new, never-before-powered-on
> > disk drive via the fictitious IN-KERNEL disklabel STRUCTURE.  But, need
> > never actually write it to the medium to allow such access (on a NetBSD box).
>
> IIUC, this is a subtle (but important) clarification.

There are some caveats, IIRC.  E.g., the fictitious disk label also "imagines"
(a fictitious) 'a' partition.  But, an attempt to "newfs /dev/rsd#a" will fail.

The only thing you can be sure of is the "whole disk" partition -- and ONLY if
you haven't altered the in-kernel instance of it WITHOUT writing that to the
medium (cuz there is no other instance!).

ISTR (many major releases ago) having to put ALL of the label information on
the medium (using disktab(5)).