Useful for Multiboot USB pen, see
http://wiki.grml.org/doku.php?id=tips#multiboot_usb_pen
grml bootid=mybootid Use specified argument as identifier for the ISO.
+ mybootid is specified in /conf/bootid.txt on the ISO.
[Note: only available since release 2010.04]
grml ignore_bootid Disable bootid verification.
[Note: only available since release 2010.04]