Date: Wed, 9 Apr 2014 08:08:04 +0100 From: Ben Morrow <ben@morrow.me.uk> To: freebsd-stable@freebsd.org Subject: Re: Note for those pulling in new ZFS feature flags Message-ID: <20140409070759.GA14719@anubis.morrow.me.uk> In-Reply-To: <20140409034636.GC5433@behemoth> References: <20140407135421.GA16385@behemoth> <CAFHbX1%2BCerhdfo-VB4dj_JZAkp79b_KD7T0TCxFWTLGFsu-Mpw@mail.gmail.com> <20140407145511.GA16747@behemoth> <alpine.BSF.2.00.1404071656540.9102@mail.fig.ol.no> <20140407153040.GA17668@behemoth> <4C688889-96C0-4B8C-82E7-ACC3FB729FAB@gromit.dlib.vt.edu> <5344BEAF.1030206@FreeBSD.org>
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Quoth Chris Nehren <cnehren+freebsd-stable@pobox.com>:
>
> Are you asking, in other words, what problems could come from
> fixing the bootcode automatically whenever it's needed? The
> immediate, obvious concern is that maybe the bits sourced to do
> so aren't valid for the pool in question[0] or don't exist. The
> latter is easy to check for of course. I'm afraid I don't know
> enough to judge the former.
>
> [0]: Although I can't imagine a situation when that'd be the
> case, that doesn't mean such a sitaution doesn't exist.
Upgrading a pool on a disk which happens to be attached to this machine
at the moment but which is supposed to boot a different architecture?
(Rather obscure, I know.)
More generally, is it possible to determine post-boot which disk the
bootloader actually ran from, and which of {gpt,}{zfs,}boot it was? It
would hardly be helpful to 'upgrade' a /boot-on-UFS machine to a ZFS
bootloader. Then there's the question of whether FreeBSD's bootstrap is in
use at all, rather than something like GRUB.
One possibility might be to put a Makefile in /boot which can be
customised as necessary; then zfs upgrade could just run 'make -C /boot
install' and assume it would DTRT.
Ben
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