[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: CD-R Bootable?

> I read something about this somewhere in my reading of other debian-powerpc
> messages, but it was in a message from Ethan and others about the technical
> reasons why it wasn't working and that the r1 CD's needed to be updated.
> I didn't completely understand the discussion, but now something clicked and
> it makes sense.  (I'm slowly figuring out this unfamiliar boot process that
> Apples use.)

The way Linux is booted on newworld Macs is roughly as follows:

- OpenFirmware will try to load something it knows to handle from the CD.
This can either be a CHRP binary, or a CHRP script. We don't know how to
turn yaboot into a CHRP binary yet, so we go for the script. 

- The script will in turn instruct OF to load and run a binary: the MacOS
ROM file, or the yaboot binary. yaboot then proceeds to load a kernel,
booting Linux (finally). 

OF looks at the script header to figure out if the script code can be
executed on this particular machine and OF version. The <COMPATIBLE>
tag in the script holds a list of machine aliases the script may run
on. The CHRP script shipped with 2.2 lacks the entry for the new iMacs, so
OF refuses to load it.

The boot cd:,\\yaboot is exactly what would have been run by the script.


Reply to: