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.Dd March 27, 2018 26.Dt ZFSBOOT 8 27.Os 28.Sh NAME 29.Nm zfsboot 30.Nd bootcode for ZFS on BIOS-based computers 31.Sh DESCRIPTION 32.Nm 33is used on BIOS-based computers to boot from a filesystem in 34a ZFS pool. 35.Nm 36is installed in two parts on a disk or a partition used by a ZFS pool. 37The first part, a single-sector starter boot block, is installed 38at the beginning of the disk or partition. 39The second part, a main boot block, is installed at a special offset 40within the disk or partition. 41Both areas are reserved by the ZFS on-disk specification for boot use. 42If 43.Nm 44is installed in a partition, then that partition should be made 45bootable using appropriate configuration and boot blocks described in 46.Xr boot 8 . 47.Sh BOOTING 48The 49.Nm 50boot process is very similar to that of 51.Xr gptzfsboot 8 . 52One significant difference is that 53.Nm 54does not currently support the GPT partitioning scheme. 55Thus only whole disks and MBR partitions, traditionally referred to as 56slices, are probed for ZFS disk labels. 57See the BUGS section in 58.Xr gptzfsboot 8 59for some limitations of the MBR scheme support. 60.Sh USAGE 61.Nm 62supports all the same prompt and configuration file arguments as 63.Xr gptzfsboot 8 . 64.Sh FILES 65.Bl -tag -width /boot/zfsboot -compact 66.It Pa /boot/zfsboot 67boot code binary 68.It Pa /boot.config 69parameters for the boot block 70.Pq optional 71.It Pa /boot/config 72alternative parameters for the boot block 73.Pq optional 74.El 75.Sh EXAMPLES 76.Nm 77is typically installed using 78.Xr dd 1 . 79To install 80.Nm 81on the 82.Pa ada0 83drive: 84.Bd -literal -offset indent 85dd if=/boot/zfsboot of=/dev/ada0 count=1 86dd if=/boot/zfsboot of=/dev/ada0 iseek=1 oseek=1024 87.Ed 88.Pp 89If the drive is currently in use, the GEOM safety will prevent writes 90and must be disabled before running the above commands: 91.Bd -literal -offset indent 92sysctl kern.geom.debugflags=0x10 93.Ed 94.Pp 95.Nm 96can also be installed in an MBR slice: 97.Bd -literal -offset indent 98gpart create -s mbr ada0 99gpart add -t freebsd ada0 100gpart bootcode -b /boot/boot0 ada0 101gpart set -a active -i 1 ada0 102dd if=/dev/zero of=/dev/ada0s1 count=2 103dd if=/boot/zfsboot of=/dev/ada0s1 count=1 104dd if=/boot/zfsboot of=/dev/ada0s1 iseek=1 oseek=1024 105.Ed 106.Pp 107Note that commands to create and populate a pool are not shown 108in the example above. 109.Sh SEE ALSO 110.Xr dd 1 , 111.Xr boot.config 5 , 112.Xr boot 8 , 113.Xr gptzfsboot 8 , 114.Xr loader 8 , 115.Xr zpool 8 116.Sh HISTORY 117.Nm 118appeared in FreeBSD 7.3. 119.Sh AUTHORS 120This manual page was written by 121.An Andriy Gapon Aq avg@FreeBSD.org . 122.Sh BUGS 123Installing 124.Nm 125with 126.Xr dd 1 127is a hack. 128ZFS needs a command to properly install 129.Nm 130onto a ZFS-controlled disk or partition. 131