ELF boot and Multiboot

[Eric W. Biederman]

SONE Takeshi <ts1 at cma.co.jp> writes:

> On Fri, Jun 13, 2003 at 06:48:55PM +0900, SONE Takeshi wrote:
> > > > If one added a (trivial) Multiboot header in the head.S,
> > > > the resulting kernel could be loaded from GRUB, while it could also
> > > > be loaded by ELF boot of LinuxBIOS and Etherboot?
> > > It probably could.
> 
> Turns out it can't.
And now you see one of the many reasons GRUB has not yet been
ported to run under LinuxBIOS.

> GRUB can't load Multiboot (or other ELF) kernel below 1MB!
> Since bzImage kernel starts at just 1MB, placing 'converter' and
> gdt elsewhere after 1MB is not a trivial task..

A bzImage had a real mode component that must be run below 1MB.

Currently I place the ramdisk at 8MB, and the converter and the real
mode code could be placed on top of that.  I do something like this
for the Itanium.

Still it is less than satisfactory to require that to happen. 0-640K
is always known to be there so we should be able to use it.

Hopefully some time will open up and I can put out another ELF
booting specification.  

Eric