[Beowulf] reboot without passing through BIOS?

[Lombard, David N]

On Wed, Jul 30, 2008 at 09:13:56AM -0700, David Mathog wrote:
> If one were to build nodes without ECC memory it would probably be a
> good idea to reboot them from time to time to clean out whatever bad
> bits might have accumulated.  It then occurred to me that doing so would
> require a trip through the BIOS on every reboot, at least on every x86
> based computer I'm familiar with.

Not since kexec was added to the kernel! kexec allows you to boot another
kernel directly from Linux.

I've also written shell scripts that allow you to use kexec to reboot from
a grub configuration file or from a PXE server.

>                                    That is not a terrible thing, but it
> made me wonder if it is really necessary.  Is there a way to configure a
> machine to reboot by having the OS pass control directly to the boot
> loader, and so skip the BIOS?

Intel's Rapid Boot Toolkit allows you to install a minimal BIOS that only
gets the wires wiggling before handing control to an arbitrary payload.
Is much faster than the normal payload, and allows complete control over
the platform boot process.  kboot is used as a sample payload to provide
for a customized Linux boot, e.g., ssh directly into the pre-OS using
keys you provided, boot from arbitrary fabric, filesystem, or remote storage.

Infiscale has a payload that enables nodes to directly boot Perceus from
Infiniband or Ethernet.

>                                An additional reason for being able to do
> this, although not so much on beowulf nodes, would be that, by loading a
> different boot loader configuration on the way down, one could choose
> which of several OS's to boot _before_ the reboot on a multi-boot
> computer.

Beyond using kexec as described above, grub directly supports this; lilo
did too.

>            For instance, some multi-boot PCs I manage in a remote
> classroom boot to windows by default, so if I want to work on their
> linux systems I have to walk over there so as to be able to select that
> option from the boot menu.

Grub above may work quite well for that.

-- 
David N. Lombard, Intel, Irvine, CA
I do not speak for Intel Corporation; all comments are strictly my own.