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[ppc] CHRP NOTE segment


From: Hollis Blanchard
Subject: [ppc] CHRP NOTE segment
Date: Sat, 25 Sep 2004 22:15:37 -0500

Currently we have this in crt0.S:
        .section ".note"
        .align  2
.note_section_header:
        .long   8
        .long   24
        .long   0x1275
        .string "PowerPC"
.note_descriptor:
        .long   0x0             /* real-mode */
        .long   0xffffffff      /* real-base */
        .long   0xffffffff      /* real-size */
        .long   0xffffffff      /* virt-base */
        .long   0xffffffff      /* virt-size */
        .long   0x00030000      /* load-base */

It's a nice idea, but unfortunately doesn't work. I see that the CHRP binding is confusing here: it requires an "ELF Note section", but it also specifies type "PT_NOTE", which if you consult elf.h is in fact a segment type. A NOTE *segment* is required.

Also, as I understand it Apple OF becomes extremely unhappy if it finds a NOTE segment. I don't remember how bad exactly but it's possible it won't boot after that. Perhaps disconnecting the power and motherboard battery to allow PRAM settings to clear will fix it (see http://www.netbsd.org/Ports/macppc/faq.html#ofw-clear). It's possible that Apple's OF attempts to reconfigure itself (according to the NOTE) but ends up in an unbootable state. IBM OF, on the other hand, requires the NOTE segment.

In any case, the code above is useless and should be removed.

-Hollis





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