make module loading by boot installboot patchable?

[Matthias Drochner <M.Drochner%fz-juelich.de@localhost>]

Since there is discussion about the robustness of modular
kernels...

If one drops a new "pxeboot" loader into an existing diskless
boot installation it fails completely. In my case it did just
reset the box when it tried to load an "nfs" module. The diskless
box does get what the DHCP server tells it to get, and this
is just pxeboot and the kernel itself.
(What happened is likely that pxeboot just TFTP'd another instance
of the kernel which it couldn't digest in some way.)

So to make a diskless system boot unattended and reliably,
module loading needs to be disabled for pxeboot in the standard
case. This could be done by a compile-time #ifdef, but to
make experiments easy we could also dedicate a bit of
the patchable x86_boot_params:bp_flags field to it, and
add an option to installboot(8) to switch it.

That's not hard, and I'm ready to do it (next year).
What do you think?

best regards
Matthias



------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
Forschungszentrum Juelich GmbH
52425 Juelich
Sitz der Gesellschaft: Juelich
Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498
Vorsitzende des Aufsichtsrats: MinDir'in Baerbel Brumme-Bothe
Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender),
Dr. Ulrich Krafft (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt,
Prof. Dr. Sebastian M. Schmidt
------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------