Etherboot in the BIOS?

steven james pyro at
Sat Aug 16 14:09:01 CEST 2003


It IS possible to render a board unbootable with a bad flash, but there
are a few protections in place.

The trickiest part is the initial loading where a fallback image is
flashed into the top of the BIOS. The fallback block can (should) be set
up as a completely independant boot image with a copy of Etherboot built

Most of the boards have a socketed flash so that the worst case scenerio
for a mis-flashed fallback is that you'll have to boot from a spare
chip, hot swap in the mis-flashed chip, and try again.

Unfortunatly, a few boards do have a soldered down flash. In those cases,
the only way to recover is to de-solder the chip (which may not be worth
the cost vs. a new board)

Once in place and functioning, the fallback should never be changed. Many
mainboards (all of the i7501 based boards for example) have a jumper that
can be set to prevent accidental flashing of the top block.

The rest of the flash contains the primary LinuxBIOS image and the
preferred boot payload (often another copy of Etherboot), and can then be
flashed at will. The worst case will be that you'll have to hit reset a
few times to cause the fallback image to boot the system.


On Fri, 15 Aug 2003, Andrew Sterling Hanenkamp wrote:

> According to the FAQ, it's possible to boot Linux using Etherboot with 
> LinuxBIOS.  This appears to be a pretty simple and straightforward 
> process, but I was wandering if it were possible to render the system 
> unbootable?  That is, is it posible that overwriting the BIOS will cause 
> boot to fail (because of misconfiguration, etc.)?  If this happens, is 
> there anyway to recover?  What are the pitfalls and how can I avoid them?
> The idea of overwriting the BIOS makes me a bit nervous, but the 
> potential benefits of this boot-up process could save us quite a bit 
> when it comes to configuring our clustered systems.
> Thanks,
> Sterling

-------------------------steven james, director of research, linux labs
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