Question on LinuxBIOS Bios Stack

Eric W. Biederman ebiederman at lnxi.com
Fri Mar 5 18:39:00 CET 2004


Heiko Joerg Schick <info at schihei.de> writes:

> Hello Eric,
> 
> I've found an an article from you about LinuxBIOS. It would
> be great if you can answer some short question about the
> project.
> 
> 
> I can remember that (I think) 6 month ago, a system call
> LOBOS was used to boot the later used Linux Kernel. Now I
> saw in the document "Flexibility in ROM: A Stackable
> Open Source BIOS" that a quite more complex firmware stack
> is used, with the following components:
> - LinuxBIOS
> - ADLO
> - Bochs BIOS
> - Grub Bootloader
> - Windows 2000, Linux, ...
> 
> I this always the case and how it is realized on other
> platforms, like PowerPC???

LinuxBIOS is the core piece that initialized the hardware.  Then it loads
and executable in the ELF file format from the rom.  That executable
can be the final kernel, or it can currently be one of the following bootloaders:
ADLO
etherboot.
Linux Kernel with LOBOS/2 kernel monte/Kexec support
FILO
9Load
OpenBIOS
....

It is very simple and flexible.  As for the PowerPC I think they are
directly loading the kernel.  All that is required of the bootloader
is that it be able to run on the bare hardware making no firmware
calls.  Like an OS typically does.

Eric



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