[SeaBIOS] BEV and bootorder

Kevin O'Connor kevin at koconnor.net
Sun Apr 15 05:19:31 CEST 2012


On Thu, Apr 12, 2012 at 01:30:36PM -0600, Steve Goodrich wrote:
> I'm working towards a goal of having specific devices be bootable, and
> *only* those devices.  For example, if my bootorder file specifies SATA
> drive 3, I do not want it to try SATA drives 0, 1, and 2, nor any other HDD
> or floppy that it finds.
> 
> My first question is: how do I do this?

There is no current way to do this.  I suppose one could code support
for a "stop boot" option to the boot order file - so that if it was
listed in the file the boot would stop after trying all options prior
to it.

> If that can't be answered, can someone explain to me the relationship
> between the bootorder file and the BEV (Boot Execution Vector) configured in
> boot.c?

All possible boot options (both BEV and BCV) are assembled in a sorted
list pointed to by boot.c:BootList.  The bootorder file alters the
default sort order of that list.  During the latter parts of the POST
phase, the BCVs are executed and only BEVs remain.  The list of BEVs
is generated from the BootList.  So, in a nutshell, the bootorder file
determines the order of the BEVs that SeaBIOS will attempt to boot
from.

-Kevin



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