NanoBSD: how to add manual upgrade "approval" / auto roll-back?

[Andrew Stevenson]

> On 16. Jul 2018, at 18:01, Lev Serebryakov <lev at FreeBSD.org> wrote:
> 
> Is it possible to make some mechanism (in loader? I don't think
> mbr/boot0 can accommodate this) which switch back active slice if boot
> into new version was not successful (not all services started, or kernel
> hangs, or network is unavailable), so it will be possible to roll-back
> upgrade by simple power cycle, without console access? Very important



I haven’t done this but, assuming you are using gptboot, can you not set the bootonce flag after upgrade? Then if the system comes up you set bootme.

Andrew