97371ba2a9
(gpt)zfsboot will read one-time boot directives from a special ZFS pool area. The area was previously described as "Boot Block Header", but currently it is know as Pad2, marked as reserved and is zeroed out on pool creation. The new code interprets data in this area, if any, using the same format as boot.config. The area is immediately wiped out. Failure to parse the directives results in a reboot right after the cleanup. Otherwise the boot sequence proceeds as usual. zfsbootcfg writes zfsboot arguments specified on its command line to the Pad2 area of a disk identified by vfs.zfs.boot.primary_pool and vfs.zfs.boot.primary_vdev kenv variables that are set by loader during boot. Please see the manual page for more. Thanks to all who reviewed, contributed and made suggestions! There are many potential improvements to the feature, please see the review for details. Reviewed by: wblock (docs) Discussed with: jhb, tsoome MFC after: 3 weeks Relnotes: yes Differential Revision: https://reviews.freebsd.org/D7612
113 lines
3.2 KiB
Groff
113 lines
3.2 KiB
Groff
.\" Copyright (c) 2016 Andriy Gapon
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd October 12, 2016
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.Dt ZFSBOOTCFG 8
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.Os
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.Sh NAME
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.Nm zfsbootcfg
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.Nd "specify zfsboot options for the next boot"
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.Sh SYNOPSIS
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.Nm
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.Ao Ar options Ac
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.Sh DESCRIPTION
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.Nm
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is used to set
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.Xr boot.config 5 Ns -style
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options to be used by
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.Xr zfsboot 8
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or
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.Xr gptzfsboot 8
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the next time the machine is booted.
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Once
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.Xr zfsboot 8
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or
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.Xr gptzfsboot 8
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reads the information, it is deleted.
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If booting fails, the machine automatically reverts to the previous
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boot configuration.
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The information is stored in a special reserved area of a ZFS pool.
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.Xr zfsboot 8
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or
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.Xr gptzfsboot 8
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read the boot option information from the first disk found in the first
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ZFS pool found.
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.Sh ENVIRONMENT
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.Bl -tag -width vfs.zfs.boot.primary_pool -compact
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.It Ev vfs.zfs.boot.primary_pool
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The
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.Xr kenv 1
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variable that identifies a pool for which the options are written.
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.It Ev vfs.zfs.boot.primary_vdev
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The
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.Xr kenv 1
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variable that identifies a disk within the pool where the options
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are written.
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.El
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.Sh EXAMPLES
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Try to boot to a new
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.Em boot environment
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without changing the
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.Cm bootfs
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property of a pool:
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.Pp
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.Dl "zfsbootcfg ""zfs:tank/ROOT/newbe:""
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.Pp
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To clear the boot options:
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.Pp
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.Dl "zfsbootcfg """"
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.Sh SEE ALSO
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.Xr boot.config 5 ,
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.Xr gptzfsboot 8 ,
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.Xr zfsboot 8
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.Sh HISTORY
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.Nm
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appeared in
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.Fx 12.0 .
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.Sh AUTHORS
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This manual page was written by
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.An Andriy Gapon Aq Mt avg@FreeBSD.org .
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.Sh CAVEATS
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At the moment,
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.Nm
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uses the
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.Ev vfs.zfs.boot.primary_pool
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and
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.Ev vfs.zfs.boot.primary_vdev
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.Xr kenv 1
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variables to determine a ZFS pool and a disk in it where the options
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are to be stored.
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The variables are set by the ZFS boot chain, so there is an assumption
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that the same boot disk is going to be used for the next reboot.
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There is no
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.Nm
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option to specify a different pool or a different disk.
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.Pp
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.Nm
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should be extended to install new
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.Xr zfsboot 8
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blocks in a ZFS pool.
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