USB Live Media

The Dark Ages

BIOS-based firmware normally required bootable CD media based on the El Torito standard. This required special authoring tools and an El Torito-compatible bootloader (such as ISOLINUX).

When not using optical media, an ISO image can be written to a device such as a USB flash drive, but must still use the El Torito format.

EFI Boot Process

EFI-based firmware can boot from CDs using either El Torito or a standard EFI removable bootloader. Since EFI firmware can read FAT32 filesystems, a standard USB flash drive can be made bootable without formatting to another filesystem like ISO 9660 or writing to a special boot sector, and one or more bootable operating systems can coexist with other read-write data on the same filesystem.

-- StephenCavilia - 29 Sep 2020