[syslinux] Booting ISO images over PXE

H. Peter Anvin hpa at zytor.com
Tue Oct 2 10:41:20 PDT 2007

Tobias Abt wrote:
> Hi,
> I looked through the documentation and the mailing list archives but
> could not yet find out whether this could be made to work.
> The task I want to use that feature for is being able to collect
> firmware updates for servers and their components and boot those
> updates from a notebook with DHCP/TFTP-Server. That would greatly
> reduce setup time for new server installations.
> The problem is that today quite a few such firmware updates do not
> fit on 1,44MB disk images and are distributed as (small) ISO images.
> Due to the number of images and the rate they are being replaced
> with new updates it would be very nice to use them as they are
> without having to convert them to HD images or something like that.

This is an FAQ.  There exist no uniform way by which ISOs can be made 
remote-bootable.  Although I could write an El Torito mode for MEMDISK, 
odds are very slim that it will continue working once the ISO boots, 
since few if any operating systems continue to use the El Torito BIOS to 
talk to the CD-ROM, and thus will find themselves confused.

It used to be that *no* operating system (including DOS) would continue 
to use El Torito, but I think there is an ELTORITO.SYS for DOS now, 
which would actually continue to work.  The question is if anything 
would actually use it.

On the latest hardware (VMX/SVM capable) one could, at least in theory, 
implement a thin hypervisor and virtualize the relevant I/O ports to 
make it appear that a real CD-ROM is out there.  Needless to say, that's 
a big effort.


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