PReP fails to boot on QEMU (current git snapshot)

[Grant Likely]

zImage.prep built from head of Linus' tree fails to boot with the error
below.

Looks like QEMU is trying to run from empty ram.  'x/32 0x8acd80' shows
nothing but zeros.  Anybody else seen this?

~/linux-2.6$ qemu-system-ppc -prep -nographic -hda ../yaboot/disk.img \
                             -kernel arch/ppc/boot/images/zImage.prep
<----snip---->
dest 100000 entry 00000200 => 100200
Load raw file into memory at 100000 689989 (000a8745) 0 (00000000)
Boot: 00040000 45870a00 00000000 00000000
Bootinfos at : 200000

Now boot it... (0)

stack: 5bfff70 malloc_base: 0 0x05800000 0x06000000
PREP boot... 100200 100000
invalid/unsupported opcode: 00 - 00 - 00 (00000000) 0x008acddc 1
ERROR: BUG caught...
Program exception
nip=0x008acddc msr=0x00092030 dar=0x00000000 dsisr=0x00000000
Stopping execution

Isolated down to somewhere in about 50 commits using bisect
(intermediate steps don't compile):  A bunch of ppc/ppc64 merge stuff
went in between.

good: ab11d1ea281e85895369ef57c5259ad8a432fabb
good: c0c0d996d08e450164adedc249c1bbbca63524ce
bad:  fd582ec88eb8d2d907876603e4ecebe6eab330d9

Details:
gcc: 3.4.4; build w/ crosstool
.config: attached (hugely cut down)
ARCH=ppc

-- 
Grant Likely, B.Sc. P.Eng.
Secret Lab Technologies Ltd.
(403) 663-0761
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