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Subject[PATCH 3.16 236/305] powerpc: Fix COFF zImage booting on old powermacs
3.16.63-rc1 review patch.  If anyone has any objections, please let me know.


From: Paul Mackerras <>

commit 5564597d51c8ff5b88d95c76255e18b13b760879 upstream.

Commit 6975a783d7b4 ("powerpc/boot: Allow building the zImage wrapper
as a relocatable ET_DYN", 2011-04-12) changed the procedure descriptor
at the start of crt0.S to have a hard-coded start address of 0x500000
rather than a reference to _zimage_start, presumably because having
a reference to a symbol introduced a relocation which is awkward to
handle in a position-independent executable. Unfortunately, what is
at 0x500000 in the COFF image is not the first instruction, but the
procedure descriptor itself, that is, a word containing 0x500000,
which is not a valid instruction. Hence, booting a COFF zImage
results in a "DEFAULT CATCH!, code=FFF00700" message from Open

This fixes the problem by (a) putting the procedure descriptor in the
data section and (b) adding a branch to _zimage_start as the first
instruction in the program.

Fixes: 6975a783d7b4 ("powerpc/boot: Allow building the zImage wrapper as a relocatable ET_DYN")
Signed-off-by: Paul Mackerras <>
Signed-off-by: Michael Ellerman <>
Signed-off-by: Ben Hutchings <>
arch/powerpc/boot/crt0.S | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/arch/powerpc/boot/crt0.S
+++ b/arch/powerpc/boot/crt0.S
@@ -15,7 +15,7 @@
RELA = 7
RELACOUNT = 0x6ffffff9

- .text
+ .data
/* A procedure descriptor used when booting this as a COFF file.
* When making COFF, this comes first in the link and we're
* linked at 0x500000.
@@ -23,6 +23,8 @@ RELACOUNT = 0x6ffffff9
.globl _zimage_start_opd
.long 0x500000, 0, 0, 0
+ .text
+ b _zimage_start

#ifdef __powerpc64__
.balign 8
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