powerpc: Change the default link address for pSeries zImage kernels

Currently we set the start of the .text section to be 4Mb for pSeries.
In situations where the zImage is > 8Mb we'll fail to boot (due to
overlapping with OF).  Move .text in a zImage from 4MB to 64MB
(well past OF).

We still will not be able to load large zImage unless we also move OF,
to that end, add a note to the zImage ELF to move OF to 32Mb.  If this
is the very first kernel booted then we'll need to move OF manually by
setting real-base.

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/boot/wrapper

@@ -138,14 +138,20 @@ objflags=-S
 tmp=$tmpdir/zImage.$$.o
 ksection=.kernel:vmlinux.strip
 isection=.kernel:initrd
+link_address='0x400000'
 
 case "$platform" in
-pmac|pseries|chrp)
+pseries)
+    platformo=$object/of.o
+    link_address='0x4000000'
+    ;;
+pmac|chrp)
     platformo=$object/of.o
     ;;
 coff)
     platformo=$object/of.o
     lds=$object/zImage.coff.lds
+    link_address='0x500000'
     ;;
 miboot|uboot)
     # miboot and U-boot want just the bare bits, not an ELF binary
@@ -190,6 +196,7 @@ ps3)
     objflags="-O binary --set-section-flags=.bss=contents,alloc,load,data"
     ksection=.kernel:vmlinux.bin
     isection=.kernel:initrd
+    link_address=''
     ;;
 ep88xc|ep405|ep8248e)
     platformo="$object/fixed-head.o $object/$platform.o"
@@ -272,7 +279,10 @@ if [ -n "$dtb" ]; then
 fi
 
 if [ "$platform" != "miboot" ]; then
-    ${CROSS}ld -m elf32ppc -T $lds -o "$ofile" \
+    if [ -n "$link_address" ] ; then
+        text_start="-Ttext $link_address --defsym _start=$link_address"
+    fi
+    ${CROSS}ld -m elf32ppc -T $lds $text_start -o "$ofile" \
 	$platformo $tmp $object/wrapper.a
     rm $tmp
 fi