In message <mtuek24a5xn.fsf@contents-vnder-pressvre.mit.edu>, "Nathan J. Willia
ms" writes:
>For systems like this, there generally isn't a "native bootloader" in
>the sense of /boot on an i386 system; just have RedBoot load and jump
>to the kernel. You need to pick an address above where RedBoot is, as
>it doesn't relocate itself or anything like that.

Okay, I'm with that so far.

And I can find a safe address by using elf tools to look at my eCos binaries,
which are just big ELF files too.  :)

(I ported Frotz to this; I now have a very nice embedded system that, uhm,
plays Zork.)

>__start, actually. Look in obs200_locore.S and read from there; there
>are a couple of obvious addresses that may need tweaking, and from
>there it jumps into initppc() in obs200_machdep.c. You should be able
>to walk the code from there and find the bits that are
>obs-specific. Once you have the console going (consinit()), you should
>be able to debug your way to happiness; before that, you may need a
>couple of debugging aids to figure out where your code is. LEDs can be
>helpful here, as can hand-crafted routines to dump a few bytes on the
>serial port in the state RedBoot left it in before consinit() runs.

Ahh!  So those would be the files to clone, then modify.

Excellent!  Now that I know which code to read, I can probably get some
traction on this.

-s