Re: [Etherboot-developers] Re: 3Com MBA+nbi image support patch

[Michael G. <mge...@so...>]

> >Aha!  Good question.  Short answer: interoperability.
> >
> >Long answer: I have an embedded system with legacy components which
> >boot using 3Com MBA ROMs.  I am designing replacement components which we
> >do not want to purchase rolls of 3Com ROMs for.  Instead we've elected to
> >go with etherboot.  However, one of the requirements is that the new and
> >legacy components must be able to coexist with no changes to the boot
> >server, hence the preceeding patch.
> >
> >It is possible to further modify the MBA probe code to support an MBA only
> >boot, but I do not have the time (nor the mandate :) to do that at
> >present.
> >
> >Thanks for your interest!
> 
> I'm kind of tickled by the idea of booting MBA images on non-3Com
> hardware. I'm like E&E just as much as M$ as long as it's FLOSS that's
> doing E&E. :-)
> 
> I am willing to accept the patch provided:
> 
> 1. It's enclosed in suitable #ifdefs so that not selecting the MBA
> option costs nothing.

Uhuh.  I will rework the $ifdefs to make it so.

> 2. Your contact address is inserted somewhere so that if someone has a
> query or wants to improve the code, they can contact you. It would be
> nice if you could continue to maintain it, but I understand that people
> move on to other projects. Just as long as someone can email you and you
> can tell them: yes that is the right fix, or sorry I'm no longer
> maintaining it, UTSL, and it's yours to maintain should you choose to
> accept the mission.

I should have this assigned as a maintenance task for the foreseeable
future and will add my contact info.

> I'll have a look over the code later. My body time is still somewhere in
> the ocean.

Thanks!

> --__--__--
> ke...@us... (Ken Yap) writes:
> 
> > I'll have a look over the code later. My body time is still somewhere in
> > the ocean.
> 
> Ken look carefully.  The code currently requires a tagged image with
> an MBA header.  I am not certain if anyone else can do anything useful
> with a hybrid like that.
> 
> Eric

Both the probe and download functions have been added to support this
hybrid header.  It is true that currently most of the code in these
functions is occupied with stripping off the MBA header and then arranging
the remaining tag so that it is palatable to the tagged probe
function.  However, there's nothing stopping someone with more ambition
from changing these functions to do the download themselves.

The problem lies in extracting the required fields from the MBA
header.  All I needed for this simple mod was the identification string
and header size fields.  However, examining the decompiled imggen binary
in more detail would reveal the necessary fields for booting a non
nbi tagged kernel.