[Beowulf] reboot without passing through BIOS?

David Mathog mathog at caltech.edu
Wed Jul 30 11:56:28 PDT 2008

Robert G. Brown wrote:

> There are several ways to accomplish this, and they can be automated.
> For example, run a script at boot time that runs a script like
> /etc/specialboot if it exists.  Then put:
> #!/bin/sh
> # cp /boot/grub/grub.conf.default /boot/grub/grub.conf
> # cp /boot/grub/grub.conf.special /boot/grub/grub.conf

These all work great for controlling from the linux side, not so well
for controlling from the Windows site.  I have seen methods like this
for Windows, but they depend upon putting grub.conf in a location where
Windows can write it.  

Ideally grub/lilo would look in the MBR, or some other block in the
first track on the boot disk, for a "boot once special" flag and field.
 If the flag was set it would read the field and then clear the flag. 
Then the tool on pretty much any OS to enable this would just be:

 read a block from disk (from some known special location)
 set the flag and field
 write the block back to disk

Easiest if it is the MBR, not hard though for any other block in the
first track. Heck, if lilo and grub could coordinate they could even use
the exact same flag and field for this purpose, so that only one tool
would be needed to accomplish it.


David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech

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