FreeBSD manual
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ISOBOOT(8) FreeBSD System Manager's Manual ISOBOOT(8)
NAME
isoboot - Boot code for hybrid ISO/USB images on BIOS-based computers
DESCRIPTION
isoboot is used on BIOS-based computers to boot from an ISO image that
has been written to a USB flash drive or other HDD-like device. isoboot
is installed in a freebsd-boot partition with mkimg(1).
IMPLEMENTATION NOTES
The El Torito standard for bootable CDs provides a 32KB "System Area" at
the beginning of an image. To create an image that is able to be booted
by the BIOS as either a CD-ROM ("ISO") and as a more HDD-like image (e.g.
on a USB flash drive) it is necessary to have both a standard El Torito
boot catalog containing a HDD-style partition table and boot code.
isoboot is intended to be placed in a GPT partition to allow the system
to find the standard FreeBSD loader(8) in the ISO filesystem later in the
image.
BOOTING
isoboot looks for an ISO filesystem image on the device it was booted
from and seeks to read either the primary FreeBSD loader(8) or kernel
from there.
SEE ALSO
mkimg(1)
HISTORY
isoboot appeared in FreeBSD 12.0.
AUTHORS
This manual page written by Benno Rice <benno@FreeBSD.org>.
FreeBSD 14.0-RELEASE-p6 March 30, 2018 FreeBSD 14.0-RELEASE-p6