[HOW TO]Unpack/Repack initramfs in zImage (update for cygwin)

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The latest version:
https://github.com/xiaolu/galaxys2_kernel_repack

update for cygwin

I hate GFW

I got a problem after repacked the new zImage.

The original size of zImage is 8MB, but the new zImage is 5MB...

Originally Posted by Chenglu

Unpack:

./k-unpack zImagexwki8 initramfs-ki8
[I] Extracting gzip'd kernel image from file: zImagexwki8 (start = 16621) 
[I] CPIO compression type detected = none | offset = 163840 
[I] Extracting non-compressed CPIO image from kernel image (offset = 163840) 
[I] Expanding CPIO archive: initramfs.cpio to initramfs-ki8.

Create newinitramfs.cpio:

./gen_initramfs.sh -o newinitramfs-ki8.cpio -u 0 -g 0 ./initramfs-ki8

or

cd initramfs-ki8
find . | cpio -o -H newc > ../newinitramfs-ki8.cpio

Edit k-repack Modified to your cross-compiler:

COMPILER=/home/xiaolu/CodeSourcery/Sourcery_G++_Lite/bin/arm-none-eabi
COMPILER_LIB=/home/xiaolu/CodeSourcery/Sourcery_G++_Lite/lib/gcc/arm-none-eabi/4.5.2

Rebuild kernel:

./k-repack zImagexwki8 newinitramfs-ki8.cpio
[I] ---------------------------kernel repacker for i9100---------------------------
 
[I] Extracting gzip'd kernel from zImagexwki8 (start = 16621) 
[I] Non-compressed CPIO image from kernel image (offset = 163840) 
[I] CPIO image MAX size:3044984 
[I] head count:3208824 
[I] Making head.img ( from 0 ~ 163840 ) 
[I] Making a tail.img ( from 3208824 ~ 13773971 ) 
[I] Current ramdsize using cat : 3045376 with required size : 3044984 
[I] Current ramdsize using gzip -fc : 1888879 with required size : 3044984 
[I] gzip -fc accepted! 
[I] Merging [head+ramdisk] + padding + tail 
[I] Now we are rebuilding the zImage 
[I] Image ---> piggy.gzip 
[I] piggy.gzip ---> piggy.gzip.o 
[I] Compiling head.o 
[I] Compiling misc.o 
[I] Compiling decompress.o 
[I] Compiling lib1funcs.o 
[I] Create vmlinux.lds 
[I] head.o + misc.o + piggy.gzip.o + decompress.o + lib1funcs.o---> vmlinux 
[I] vmlinux ---> zImage 
[I] Re-compiled to new_zImage 
[I] Cleaning up... 
[I] finished...

Resources form GT-I9100_OpenSource_Update2(https://opensource.samsung.com )

initramfs-xwki8-cwm5.0.2.6.zip is modified initramfs for xwki8 stock kernel.

You are my hero
Thanks for making it

Originally Posted by rock_shen

I got a problem after repacked the new zImage.

The original size of zImage is 8MB, but the new zImage is 5MB...

No problem,CPIO image is gzipped

Originally Posted by rock_shen

I got a problem after repacked the new zImage.

The original size of zImage is 8MB, but the new zImage is 5MB...

use command Filled to 8387840 bytes

dd if=new_zImage of=zImage bs=8387840 conv=sync

I have writed a script for easy repacking/unpacking/padding

#!/bin/sh

REUNPACK=$1

if [ $REUNPACK == repack ]; then
cd initramfs_root
find . | cpio -o -H newc > ../initramfs.cpio 
cd ..
./k-repack zImage initramfs.cpio
fi;

if [ $REUNPACK == unpack ]; then
./k-unpack zImage 
fi;

if [ $REUNPACK == cpio ]; then
cd initramfs_root
find . | cpio -o -H newc > ../initramfs.cpio 
fi;

if [ $REUNPACK == padding ]; then
rm -rf zImage
dd if=new_zImage of=zImage bs=8387840 conv=sync
fi;

if [ $REUNPACK == clean ]; then
rm -rf zImage initramfs_root initramfs.cpio new_zImage
echo "Done!"
fi;

Originally Posted by netchip

I have writed a script for easy repacking/unpacking/padding

#!/bin/sh

REUNPACK=$1

if [ $REUNPACK == repack ]; then
cd initramfs_root
find . | cpio -o -H newc > ../initramfs.cpio 
cd ..
./k-repack zImage initramfs.cpio
fi;

if [ $REUNPACK == unpack ]; then
./k-unpack zImage 
fi;

if [ $REUNPACK == cpio ]; then
cd initramfs_root
find . | cpio -o -H newc > ../initramfs.cpio 
fi;

if [ $REUNPACK == padding ]; then
rm -rf zImage
dd if=new_zImage of=zImage bs=8387840 conv=sync
fi;

if [ $REUNPACK == clean ]; then
rm -rf zImage initramfs_root initramfs.cpio new_zImage
echo "Done!"
fi;

good work

Originally Posted by Chenglu

I hate GFW

haha
me too

Originally Posted by guaiwujia

haha
me too

hiahia