[Miscellaneous Android Development] finlessbob:
Here are the sripts I used. Again they worked fine on boot.img

upack:

echo 'Checking for uImage magic word...'
MAGIC=`dd if="${UIMAGE}" ibs=4 count=1 | hexdump -v -e '1/1 "%02X"'`
[ '27051956' != "${MAGIC}" ] && { echo 'Not a uImage.' ; exit 1 ; }

# extract data from uImage
echo 'uImage recognized.'
echo 'Extracting data...'
DATAFILE='uImage.data'
dd if="${UIMAGE}" of="${DATAFILE}" ibs=64 skip=1

# check for ARM mach type ( xx 1C A0 E3 xx 10 81 E3 )
# http://www.simtec.co.uk/products/SWLINUX/files/booting_article.html#d0e600
echo 'Checking for ARM mach-type...'
MAGIC=`dd if="${DATAFILE}" ibs=1 skip=1 count=3 | hexdump -v -e '1/1 "%02X"'`
[ '1CA0E3' = "${MAGIC}" ] && {
MAGIC=`dd if="${DATAFILE}" ibs=1 skip=5 count=3 | hexdump -v -e '1/1 "%02X"'`
[ '1081E3' = "${MAGIC}" ] && {
echo 'ARM mach-type header recognized.'
echo 'Extracting mach-type header...'
dd if="${DATAFILE}" of="uImage.mach-type" ibs=8 count=1
ARCH=$(hexdump -v -e '1/1 "%02X "' uImage.mach-type); echo "The mach-type is: $ARCH"
echo 'Stripping mach-type header...'
TMPFILE='uImage.tmp'
dd if="${DATAFILE}" of="${TMPFILE}" ibs=8 skip=1
rm -f "${DATAFILE}"
mv "${TMPFILE}" "${DATAFILE}"
}
}

TMPFILE='Image'
echo 'Checking for zImage...'
MAGIC=`dd if="${DATAFILE}" ibs=4 skip=9 count=1 | hexdump -v -e '1/1 "%02X"'`
[ '18286F01' = "${MAGIC}" ] && {
START=`dd if="${DATAFILE}" ibs=4 skip=10 count=1 | hexdump -v -e '1/4 "%08X"'`
END=`dd if="${DATAFILE}" ibs=4 skip=11 count=1 | hexdump -v -e '1/4 "%08X"'`
#
SIZE=$(( 0x${END} - 0x${START} ))
#
echo "zImage recognized with start 0x${START}, end 0x${END} and size ${SIZE}."
TMPFILE='zImage'
}
mv "${DATAFILE}" "${TMPFILE}"

echo ">>> ${UIMAGE} extracted to ${TMPFILE}"

inputfile=${TMPFILE}-ext

unlzma < ${TMPFILE} > $inputfile
echo ">>> ${TMPFILE} unlzma'd to $inputfile"

start=`grep -a -b -m 1 --only-matching '070701' $inputfile | head -1 | cut -f 1 -d :`
end=`grep -a -b -m 1 --only-matching 'TRAILER!!!' $inputfile | head -1 | cut -f 1 -d :`

if [ ! -z $start ] || [ ! -z $end ]; then
#11 bytes = length of TRAILER!!! zero terminated string, fixes premature end of file warning in CPIO
end=$((end + 14))
[ -z $DEBUG ] || echo "-D- Kernel start = $start"
[ -z $DEBUG ] || echo "-D- Kernel end = $end"
count=$((end - start))

if (($count < 0)); then
echo "-E- Couldn't match start/end of the initramfs image."
exit 1
fi

echo "Extracting initramfs image (start = $start, end = $end)"
dd if=$inputfile of=initramfs.cpio bs=1 skip=$start count=$count
else
echo "-E- No CPIO image found in $inputfile."
fi

rm -rf initramfs
mkdir initramfs
cd initramfs
cpio -i --no-absolute-filenames < ../initramfs.cpio
echo "initramfs.cpio extracted"
cd ..
chmod -R 777 initramfs

Here is repack:

cd initramfs
find . -print0 | cpio --null -ov --format=newc > ../initramfs.new.cpio
cd ..

oldsize=`ls -l initramfs.cpio | awk '{ print $5 }'`
newsize=`ls -l initramfs.new.cpio | awk '{ print $5 }'`

if [ $newsize -gt $oldsize ]; then
echo "New initramfs is too big ($newsize vs $oldsize)"
exit 1
else
freesize=$((oldsize - $newsize))
echo "New initramfs is $newsize bytes ($freesize bytes spare)"

fi

start=`grep -a -b -m 1 --only-matching '070701' Image-ext | head -1 | cut -f 1 -d :`
end=$((`grep -a -b -m 1 --only-matching 'TRAILER!!!' Image-ext | head -1 | cut -f 1 -d :` + 14))
count=$((end - start))

echo "Adding padding to end of initramfs.new.cpio"
cp initramfs.new.cpio initramfs.new.cpio.pad
dd if=/dev/zero bs=1 count=$freesize >> initramfs.new.cpio.pad

echo "Adding initramfs.new.cpio to kernel (start = $start, end = $end)"
dd if=Image-ext bs=1 count=$start > Image-ext.new
cat initramfs.new.cpio.pad >> Image-ext.new
dd if=Image-ext bs=1 skip=$((end)) >> Image-ext.new

echo "Compressing kernel to LZMA"
lzma < Image-ext.new > Image.new

echo "Making uImage"
mkimage -A arm -O linux -T kernel -C lzma -a 80008000 -e 80008000 -d Image.new -n Kyorakernel uImage.new

Thanks,

Bob