[dschuetz]

You know, once a machine is running, you can do everything else that's limited by your own imagination.

I've been trying to figure out how a powerpc machine is being booted so that I can insert my own 'hello world' OS. Sure there is a BIOS equivalent somewhere in there, but how to figure out how and when to talk to it?

Booting x86 might seem like nothing, but booting some old SPARC for instance seems like black magic to me.

[pjc50]

I guess it all depends on the documentation. Sun's is excellent e.g.: http://www.bitsavers.org/pdf/sun/sun3/Sun-3_Customer_Mainten... - on the Sun 3/60 you have a rather nice boot ROM which does similar things to UEFI but without the drama. It will let you netboot it over tftp, for example.

Which sort of PPC machine is it? Have you already managed to get e.g. NetBSD running on it?

[dschuetz]

Powermac g5 and/or power6. I got a CLFS kernel version 3.16 to boot and run (insanely fast) on the g5, but power6 is completely mysterious to me. There is some sort of RHEL linux based firmware running on it, but it seems there is no way to make it boot anything other than what's officially supported.