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 13.1-RELEASE-p6         March 30, 2018         FreeBSD 13.1-RELEASE-p6