Re: Grub2 please help

[Lennart Sorensen]

On Sun, Jul 24, 2016 at 07:38:53PM +0200, address@hidden wrote:
> I  am searching and finding info how chainloading whole ISO to using his 
> original bootloader. As well as Ubuntu ISO, Puppy ISO, Windows install ISO 
> and similarly. I spent much time and i did not successful and erudite man 
> from local Ubuntu forum wrote that is impossible. I am unbelieving :-) and 
> so ask to you as development team.

If the software expects to read an ISO, then it expects to talk to some
hardware optical drive.

Tools like unetbootin makes things work by knowing how each image it
supports works, and extracting required boot files and booting them
differently than the ISO would (the ISO tends to use el torito boot),
and relying on the thing being booted to work without an optical drive
(many linux installers support ISO files on USB sticks after all).

So since the OS being booted has native drivers for acciding the optical
drive to read the ISO it is supposed to be booted from, unless you
implement a virtualmachine/hypervisor that fully emulates the hardware
of that optical drive, you are not going to make the OS believe there
is an optical drive there.  Of course at that point you are not installing
on the native machine anymore, which probably defeats the purpose.

chainloading works for OSs on a hard disk because everything involved
expects to be run from a harddrive.  There is nothing that has to be
emulated.

So really, the claim that it can't be done is correct.

There exists a USB key you can buy which has a lot of smarts inside
it which emulates a full USB optical drive using an ISO selected from
the USB key.  That works, because it looks exactly like a physical USB
optical drive.  As long as the OS supports USB, it would work.  But pure
software, it can't be done.  Anything you do, will be bypassed by any
real OS (so DOS you can probably get away with tricking with BIOS hooks),.

-- 
Len Sorensen