[syslinux] Warm boot ISO image from Linux

[H. Peter Anvin]

On 03/17/2015 04:07 PM, Curt Brune via Syslinux wrote:
> Greetings!
> 
> First big thanks to the Syslinux community.  My project, the Open
> Network Install Environment (ONIE), is using isolinux to great
> effect.  Works great.
> 
> I have a crazy idea I want to bounce off of you folks.
> 
> Idea: I want to "warm boot" an ISO image from Linux.
> 
> By "warm boot" I mean start executing the code (isolinux) from the
> ISO without rebooting and going through the BIOS.
> 
> This is "somewhat" like kexec, but instead of jumping into a new Linux
> kernel it would be jumping into whatever code the ISO image has.
> 
> Imagine a user space command "iso-kexec" existed for this purpose and
> a work flow like this:
> 
>   linux:$ wget http://archive.ubuntu.com/ubuntu/dists/trusty-updates/main/installer-amd64/current/images/netboot/mini.iso
>   linux:$ sudo iso-kexec mini.iso
>   [ isolinux starts running from the ISO image .... ]
> 
> Part of my brain says "it is all just software, so it must be
> possible".  I can see needing to make a new Linux syscall, setting up
> a "boot-like" context in which the ISO can be read and executed.  Lots
> of details I'm sure.
> 
> Any thoughts from folks who are familiar with the core/isolinux.asm
> code?  Is this idea too crazy?
> 

In theory it can already be done with kexec.  In practice it almost
never works well.

	-hpa