powerpc: Make COFF zImages for old 32-bit powermacs

This adds code to build zImage.coff and/or zImage.initrd.coff when
CONFIG_PPC32 and CONFIG_PPC_PMAC are defined.  It also restructures
the OF client code and adds some workarounds for OF quirks on the
older machines.

Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 13 insertions, 8 deletions

diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S
index d2f2ace56cd3..e0192c26037b 100644
--- a/arch/powerpc/boot/crt0.S
+++ b/arch/powerpc/boot/crt0.S
@@ -12,17 +12,23 @@
 #include "ppc_asm.h"
 
         .text
+        /* a procedure descriptor used when booting this as a COFF file */
+_zimage_start_opd:
+        .long   _zimage_start, 0, 0, 0
+
         .globl  _zimage_start
 _zimage_start:
+        /* Work out the offset between the address we were linked at
+           and the address where we're running. */
         bl      1f
-
-1:
-        mflr    r0
+1:      mflr    r0
         lis     r9,1b@ha
         addi    r9,r9,1b@l
         subf.   r0,r9,r0
-        beq     3f
+        beq     3f              /* if running at same address as linked */
 
+        /* The .got2 section contains a list of addresses, so add
+           the address offset onto each entry. */
         lis     r9,__got2_start@ha
         addi    r9,r9,__got2_start@l
         lis     r8,__got2_end@ha
@@ -32,15 +38,14 @@ _zimage_start:
         srwi.   r8,r8,2
         mtctr   r8
         add     r9,r0,r9
-2:
-        lwz     r8,0(r9)
+2:      lwz     r8,0(r9)
         add     r8,r8,r0
         stw     r8,0(r9)
         addi    r9,r9,4
         bdnz    2b
 
-3:
-        lis     r9,_start@h
+        /* Do a cache flush for our text, in case OF didn't */
+3:      lis     r9,_start@h
         add     r9,r0,r9
         lis     r8,_etext@ha
         addi    r8,r8,_etext@l