bsdlabel: add legacy notice

[emaste]

Summary

BSD disk labels should be avoided on new installations.

There is no concrete plan to remove BSD label support from FreeBSD but
that will happen at some point in the future.

[emaste]

I might want to deprecate and remove bsdlabel first, due to PR276517 - BSD label manipulation via gpart does not have the same issue.

[emaste]

Make the deprecation notice for bsdlabel explicit. Also remove comment about legacy-ness of MBR/BSD disklabels, this man page isn't the right place for such a note, and there's work to do elsewhere first (e.g. having a stronger preference for not-MBR/bsdlabel in the installer).

[imp]

Bsdlabel, the program, was supposed to be completely replaced by gpart, etc so this shouldn't be a surprise.

[fuz]

I'll go ahead and provide a port for the bsdlabel utility so it remains available for legacy use cases.

[emaste]

In D43563#993865, @fuz wrote:

I'll go ahead and provide a port for the bsdlabel utility so it remains available for legacy use cases.

Thanks -- I will not disconnect or remove it before that's done.

[rgrimes]

First point, a manpage addition is pointless unless you have the binary emit a warning when invoked. Second how does one execute bsdlabel -e -A with gpart?

[emaste]

In D43563#993887, @rgrimes wrote:

First point, a manpage addition is pointless unless you have the binary emit a warning when invoked.

Sure, that can be added too, perhaps as a subsequent commit.

Second how does one execute bsdlabel -e -A with gpart?

One doesn't - one would need to install the port that @fuz will create.

[emaste]

Add reference to newly created freebsd-bsdlabel package

[emaste]

Mention BSD partitioning scheme - what gpart uses to refer to BSD disklabels

[emaste]

DEPRECATION NOTICE
bsdlabel is deprecated and is not available in FreeBSD 15.0 or later. Use gpart(8) instead (with the BSD partitioning scheme), or install the freebsd-bsdlabel port or package.