[syslinux] USB stick meets ISO system

[H. Peter Anvin]

Bernd Blaauw wrote:
> FreeDOS is also able to do so but that's because the CD redirector 
> (SHSUCDX) allows stacking,
> thus first mounting the CD, then the ISO that's on the CD. The init 
> scripts of the various (linux-)distributions need to contain code to 
> mount (not: boot) the ISO, then find the rest of the scripts or programs 
> inside the ISO and run them.
> 
> To boot a random ISO that's an image of a bootable operating system, 
> only GRUB and Smart Boot Manager come to mind with respect to 
> implementing a software built 'boot iso9660' bios stack.
> 
> Not even projects like LinuxBIOS have a CD booting stack, instead they 
> support reading the isolinux.cfg and from there find the (Linux)kernel 
> that needs to be run. Can't backup this claim with proof though, it's 
> just something I recall having read some years ago.

The real problem, once again, is that virtually no operating systems
continue to talk to the CD through the El Torito stack, so no matter
what the bootloader does, without support from the operating system it's
all for naught.  Otherwise it would be reasonably easy to extend MEMDISK
to support isos, but as it is, it's pretty pointless.  There is, of
course, also the issue of size.

	-hpa