Syslinux - Dec 2006 - Extract ElTorio No Emulation image and boot from PXE ?

Extract ElTorio No Emulation image and boot from PXE ?

Is this possible, can PXELINUX + MEMDISC intercept the BIOS calls and 
pretend to the 3rd party No Emulation image to be loading the data from 
a CD (but instead copy from memory).

The driver would be a Real Mode driver and use some part of memory above 
1Mb to store the data.

I would expect this to be risky, especially if the No Emulation image 
writes over the same (above 1Mb) location.  However maybe it would be 
possible to run the BIOS driver it in a debug/checking mode which 
checksumed its working area and the image and checked it before each 
access, beeping and rebooting if it detected a corruption.  Maybe some 
parameters could be used to shift where above 1Mb the image it copied to.

It would also be sure nice to print out a list of access the No 
Emulation image makes of the BIOS to retrieve data.


Interested in your comments,

Darryl

Darryl L. Miles wrote:
> Extract ElTorio No Emulation image and boot from PXE ?
> 
> Is this possible, can PXELINUX + MEMDISC intercept the BIOS calls and 
> pretend to the 3rd party No Emulation image to be loading the data from 
> a CD (but instead copy from memory).
> 
> The driver would be a Real Mode driver and use some part of memory above 
> 1Mb to store the data.
> 
> I would expect this to be risky, especially if the No Emulation image 
> writes over the same (above 1Mb) location.  However maybe it would be 
> possible to run the BIOS driver it in a debug/checking mode which 
> checksumed its working area and the image and checked it before each 
> access, beeping and rebooting if it detected a corruption.  Maybe some 
> parameters could be used to shift where above 1Mb the image it copied to.
> 
> It would also be sure nice to print out a list of access the No 
> Emulation image makes of the BIOS to retrieve data.
> 
It would definitely be possible (and not even all that hard) to write a 
"MEMISO" driver similar to MEMDISK which would do not just No
Emulation
but could probably do the full El Torito stack just fine.

There is just one small problem: just about every OS out there, 
including DOS, stops using El Torito after booting and looks for the 
hardware directly.  At that point, you'd have to have either a 
MEMISO-specific CD-ROM driver or an El Torito real mode CD-ROM driver, 
or you're stuck.

	-hpa