1.\" Copyright (c) 2014 Andriy Gapon <avg@FreeBSD.org> 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd March 27, 2018 28.Dt ZFSBOOT 8 29.Os 30.Sh NAME 31.Nm zfsboot 32.Nd bootcode for ZFS on BIOS-based computers 33.Sh DESCRIPTION 34.Nm 35is used on BIOS-based computers to boot from a filesystem in 36a ZFS pool. 37.Nm 38is installed in two parts on a disk or a partition used by a ZFS pool. 39The first part, a single-sector starter boot block, is installed 40at the beginning of the disk or partition. 41The second part, a main boot block, is installed at a special offset 42within the disk or partition. 43Both areas are reserved by the ZFS on-disk specification for boot use. 44If 45.Nm 46is installed in a partition, then that partition should be made 47bootable using appropriate configuration and boot blocks described in 48.Xr boot 8 . 49.Sh BOOTING 50The 51.Nm 52boot process is very similar to that of 53.Xr gptzfsboot 8 . 54One significant difference is that 55.Nm 56does not currently support the GPT partitioning scheme. 57Thus only whole disks and MBR partitions, traditionally referred to as 58slices, are probed for ZFS disk labels. 59See the BUGS section in 60.Xr gptzfsboot 8 61for some limitations of the MBR scheme support. 62.Sh USAGE 63.Nm 64supports all the same prompt and configuration file arguments as 65.Xr gptzfsboot 8 . 66.Sh FILES 67.Bl -tag -width /boot/zfsboot -compact 68.It Pa /boot/zfsboot 69boot code binary 70.It Pa /boot.config 71parameters for the boot block 72.Pq optional 73.It Pa /boot/config 74alternative parameters for the boot block 75.Pq optional 76.El 77.Sh EXAMPLES 78.Nm 79is typically installed using 80.Xr dd 1 . 81To install 82.Nm 83on the 84.Pa ada0 85drive: 86.Bd -literal -offset indent 87dd if=/boot/zfsboot of=/dev/ada0 count=1 88dd if=/boot/zfsboot of=/dev/ada0 iseek=1 oseek=1024 89.Ed 90.Pp 91If the drive is currently in use, the GEOM safety will prevent writes 92and must be disabled before running the above commands: 93.Bd -literal -offset indent 94sysctl kern.geom.debugflags=0x10 95.Ed 96.Pp 97.Nm 98can also be installed in an MBR slice: 99.Bd -literal -offset indent 100gpart create -s mbr ada0 101gpart add -t freebsd ada0 102gpart bootcode -b /boot/boot0 ada0 103gpart set -a active -i 1 ada0 104dd if=/dev/zero of=/dev/ada0s1 count=2 105dd if=/boot/zfsboot of=/dev/ada0s1 count=1 106dd if=/boot/zfsboot of=/dev/ada0s1 iseek=1 oseek=1024 107.Ed 108.Pp 109Note that commands to create and populate a pool are not shown 110in the example above. 111.Sh SEE ALSO 112.Xr dd 1 , 113.Xr boot.config 5 , 114.Xr boot 8 , 115.Xr gptzfsboot 8 , 116.Xr loader 8 , 117.Xr zpool 8 118.Sh HISTORY 119.Nm 120appeared in FreeBSD 7.3. 121.Sh AUTHORS 122This manual page was written by 123.An Andriy Gapon Aq avg@FreeBSD.org . 124.Sh BUGS 125Installing 126.Nm 127with 128.Xr dd 1 129is a hack. 130ZFS needs a command to properly install 131.Nm 132onto a ZFS-controlled disk or partition. 133