[RFC] addnote and pmac

[Benjamin Herrenschmidt]

On Mon, 2005-08-08 at 11:27 -0700, Geoff Levand wrote:
> I found that my Mac G5 wouldn't boot with a zImage modified by 
> addnote.  It worked OK when the image wasn't run through addnote 
> though.  I took just a brief look at addnote.c, and it seems this 
> step is specific to the OF implementation, or could it be needed 
> by older tool chains?
> 
> At any rate, by default it is run for all zImage builds, which 
> we'll need to change to support at least some machines.  Below is 
> what I got working, but someone more familiar with the boot 
> makefile and the needs of other machines could certainly do 
> better.

The problem is that your G5 does understand the added Note header but
doesn't like it's content.

IBM Open Firmware only works properly in real mode, while Apple's only
works properly in virtual mode. The Note header is set to real mode,
thus causing Apple's OF to do a double-reboot into a mode where it craps
itself. There is no way unfortunately to "fix" that other than
generating two zImages, or better, having the distro add the Note
section for IBM machines at zImage install time.

Note that your patch is wrong, as this has nothing to do with iSeries,
but it's a pSeries issue. But since you can built kernels images that
can be booted on both a G5 and a pSeries, using a CONFIG_ option for
that isn't a good solution anyway.

Ben.