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linux/arch/powerpc/boot/wrapper
David Gibson cd197ffcf1 [POWERPC] zImage: Cleanup and improve zImage entry point
This patch re-organises the way the zImage wrapper code is entered, to
allow more flexibility on platforms with unusual entry conditions.
After this patch, a platform .o file has two options:

1) It can define a _zimage_start, in which case the platform code gets
   control from the very beginning of execution.  In this case the
   platform code is responsible for relocating the zImage if necessary,
   clearing the BSS, performing any platform specific initialization, and
   finally calling start() to load and enter the kernel.

2) It can define platform_init().  In this case the generic crt0.S
   handles initial entry, and calls platform_init() before calling
   start().  The signature of platform_init() is changed, however, to
   take up to 5 parameters (in r3..r7) as they come from the platform's
   initial loader, instead of a fixed set of parameters based on OF's
   usage.

   When using the generic crt0.S, the platform .o can optionally
   supply a custom stack to use, using the BSS_STACK() macro.  If this
   is not supplied, the crt0.S will assume that the loader has
   supplied a usable stack.

In either case, the platform code communicates information to the
generic code (specifically, a PROM pointer for OF systems, and/or an
initrd image address supplied by the bootloader) via a global
structure "loader_info".

In addition the wrapper script is rearranged to ensure that the
platform .o is always linked first.  This means that platforms where
the zImage entry point is at a fixed address or offset, rather than
being encoded in the binary header can be supported using option (1).

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-03-13 13:35:03 +11:00

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#!/bin/sh
# Copyright (C) 2006 Paul Mackerras, IBM Corporation <paulus@samba.org>
# This program may be used under the terms of version 2 of the GNU
# General Public License.
# This script takes a kernel binary and optionally an initrd image
# and/or a device-tree blob, and creates a bootable zImage for a
# given platform.
# Options:
# -o zImage specify output file
# -p platform specify platform (links in $platform.o)
# -i initrd specify initrd file
# -d devtree specify device-tree blob
# -s tree.dts specify device-tree source file (needs dtc installed)
# -c cache $kernel.strip.gz (use if present & newer, else make)
# -C prefix specify command prefix for cross-building tools
# (strip, objcopy, ld)
# -D dir specify directory containing data files used by script
# (default ./arch/powerpc/boot)
# -W dir specify working directory for temporary files (default .)
# defaults
kernel=
ofile=zImage
platform=of
initrd=
dtb=
dts=
cacheit=
# cross-compilation prefix
CROSS=
# directory for object and other files used by this script
object=arch/powerpc/boot
# directory for working files
tmpdir=.
usage() {
echo 'Usage: wrapper [-o output] [-p platform] [-i initrd]' >&2
echo ' [-d devtree] [-s tree.dts] [-c] [-C cross-prefix]' >&2
echo ' [-D datadir] [-W workingdir] [vmlinux]' >&2
exit 1
}
while [ "$#" -gt 0 ]; do
case "$1" in
-o)
shift
[ "$#" -gt 0 ] || usage
ofile="$1"
;;
-p)
shift
[ "$#" -gt 0 ] || usage
platform="$1"
;;
-i)
shift
[ "$#" -gt 0 ] || usage
initrd="$1"
;;
-d)
shift
[ "$#" -gt 0 ] || usage
dtb="$1"
;;
-s)
shift
[ "$#" -gt 0 ] || usage
dts="$1"
;;
-c)
cacheit=y
;;
-C)
shift
[ "$#" -gt 0 ] || usage
CROSS="$1"
;;
-D)
shift
[ "$#" -gt 0 ] || usage
object="$1"
;;
-W)
shift
[ "$#" -gt 0 ] || usage
tmpdir="$1"
;;
-?)
usage
;;
*)
[ -z "$kernel" ] || usage
kernel="$1"
;;
esac
shift
done
if [ -n "$dts" ]; then
if [ -z "$dtb" ]; then
dtb="$platform.dtb"
fi
dtc -O dtb -o "$dtb" -b 0 -V 16 "$dts" || exit 1
fi
if [ -z "$kernel" ]; then
kernel=vmlinux
fi
platformo=$object/"$platform".o
lds=$object/zImage.lds
ext=strip
objflags=-S
tmp=$tmpdir/zImage.$$.o
ksection=.kernel:vmlinux.strip
isection=.kernel:initrd
case "$platform" in
pmac|pseries|chrp)
platformo=$object/of.o
;;
pmaccoff)
platformo=$object/of.o
lds=$object/zImage.coff.lds
;;
miboot|uboot)
# miboot and U-boot want just the bare bits, not an ELF binary
ext=bin
objflags="-O binary"
tmp="$ofile"
ksection=image
isection=initrd
;;
esac
vmz="$tmpdir/`basename \"$kernel\"`.$ext"
if [ -z "$cacheit" -o ! -f "$vmz.gz" -o "$vmz.gz" -ot "$kernel" ]; then
${CROSS}objcopy $objflags "$kernel" "$vmz.$$"
gzip -f -9 "$vmz.$$"
if [ -n "$cacheit" ]; then
mv -f "$vmz.$$.gz" "$vmz.gz"
else
vmz="$vmz.$$"
fi
fi
case "$platform" in
uboot)
rm -f "$ofile"
version=`${CROSS}strings "$kernel" | grep '^Linux version [-0-9.]' | \
cut -d' ' -f3`
if [ -n "$version" ]; then
version="-n Linux-$version"
fi
mkimage -A ppc -O linux -T kernel -C gzip -a 00000000 -e 00000000 \
$version -d "$vmz.gz" "$ofile"
if [ -z "$cacheit" ]; then
rm -f $vmz.gz
fi
exit 0
;;
esac
addsec() {
${CROSS}objcopy $4 $1 \
--add-section=$3="$2" \
--set-section-flags=$3=contents,alloc,load,readonly,data
}
addsec $tmp "$vmz.gz" $ksection $object/empty.o
if [ -z "$cacheit" ]; then
rm -f "$vmz.gz"
fi
if [ -n "$initrd" ]; then
addsec $tmp "$initrd" $isection
fi
if [ -n "$dtb" ]; then
addsec $tmp "$dtb" .kernel:dtb
if [ -n "$dts" ]; then
rm $dtb
fi
fi
if [ "$platform" != "miboot" ]; then
${CROSS}ld -m elf32ppc -T $lds -o "$ofile" \
$platformo $tmp $object/wrapper.a
rm $tmp
fi
# post-processing needed for some platforms
case "$platform" in
pseries|chrp)
$object/addnote "$ofile"
;;
pmaccoff)
entry=`objdump -f "$ofile" | grep '^start address ' | \
cut -d' ' -f3`
${CROSS}objcopy -O aixcoff-rs6000 --set-start "$entry" "$ofile"
$object/hack-coff "$ofile"
;;
esac