xref: /illumos-gate/usr/src/man/man7/isoboot.7 (revision bbf215553c7233fbab8a0afdf1fac74c44781867)
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25.Dd March 30, 2018
26.Dt ISOBOOT 7
27.Os
28.Sh NAME
29.Nm isoboot
30.Nd Boot code for hybrid ISO/USB images on BIOS-based computers
31.Sh DESCRIPTION
32.Nm
33is used on BIOS-based computers to boot from an ISO image that has
34been written to a USB flash drive or other HDD-like device.
35.Nm
36is installed in a
37.Cm x86 Boot
38partition with
39.Xr installboot 8 .
40.Sh IMPLEMENTATION NOTES
41The El Torito standard for bootable CDs provides a 32KB "System Area"
42at the beginning of an image.
43To create an image that is able to be booted by the BIOS as either a
44CD-ROM ("ISO") and as a more HDD-like image (e.g. on a USB flash drive)
45it is necessary to have both a standard El Torito boot catalog
46containing a HDD-style partition table and boot code.
47.Nm
48is intended to be placed in a MBR x86 boot partition to allow the system to find
49the standard
50.Fx
51.Xr loader 7
52in the ISO filesystem later in the image.
53.Sh BOOTING
54.Nm
55looks for an ISO filesystem image on the device it was booted from and
56seeks to read the primary illumos
57.Xr loader 7
58from there.
59.Sh SEE ALSO
60.Xr installboot 8
61.Sh HISTORY
62.Nm
63appeared in FreeBSD 12.0.
64.Sh AUTHORS
65This manual page written by
66.An Benno Rice Aq benno@FreeBSD.org .
67