[BULK] RFC: Generic shadow mechanism useable from a payload

Eric W. Biederman ebiederman at lnxi.com
Wed Jan 26 16:34:00 CET 2005


Adam Sulmicki <adam at cfar.umd.edu> writes:

> On Wed, 26 Jan 2005, Richard Smith wrote:
> > I wonder if we could not just set things up where the ELF loader just
> > loas it into the right spot in the first place.  Perhaps that
> > overwrites where the ELF code lives?
> 
> if the ram/shadowing was setup correctly _before_ payload is started, then
> perhaps.

Which it should be fairly universally doable with freebios2.
 
> but you still need to execute the switch to real mode code.
> 
> perhaps you could do that by the means of more elaborate elf header which tells
> 
>  	* load loader.s here
>  	* load pc bios here
>  	* load video bios here
>  	* jump to loader.s
> 
> as far as I belive elf should spport loading multiple segments into arbirary
> places in ram.

Yes you can do that with ELF.

The big gotcha is going to be that there are pirq tables current
stored at 0xf0000 that you are not going to want to stomp.

The fun question.  Can I make the bochs bios useable on a system
after the linux kernel has run.  Load it with kexec and then boot windows?

If LinuxBIOS is the native bios this should be no extra challenge.  If the
native BIOS is something else life gets a little more interesting.

Eric



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