boot0cfg on does not set default selection on gmirror device

[Patrick M. Hausen]

Hi, all,

> Am 21.10.2016 um 16:41 schrieb Warner Losh <imp at bsdimp.com>:
> Any chance you can migrate to using gpart? Is boot0cfg still
> referenced in NanoBSD somewhere?

Not in NanoBSD but how would you configure boot0's default
slice with gpart? It doesn't pay attention to the "active" flag.
See Miroslav's mails for all the details.

gpart would only be an option if we did not use the FreeBSD
boot manager. But we need the "F1 ..., F2 ..." prompt, because
being able to roll back to the last known-good system via the
console is the entire point of using this NanoBSD setup.
There's a presentation on the EuroBSDCon 2010 page about
motivation and setup. Wonder who did that talk ... :-)))

BTW: thanks, Miroslav. As for your question: it does work on
the only two systems that use hardware RAID, yet have a
gmirror built of only a single component to get consistent
device names accross all servers.

I'm not quite sure if it works from time to time, I've come to
accept the "kern.geom.debugflags" dance.

I had opened a similar discussion years ago for 7.x/8.x and
I was told that geom was to provide an API for fdisk, boot0cfg
and friends to manipulate the MBR. Because back in the days
boot0cfg and fdisk both threw an error message when trying
to work on a whole-disk mirror.
I thought that was long solved - at least no error, anymore.
But it's still not working in 10.x.

Thanks to all and take care,
Patrick
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