Seems I finally managed to build and flash my own JB kernel for the TF300T ! :good:
This will just be a quick and dirty wrap-up of what I did as my spare time is somewhat limited.
Hope to be able to make it more structured and with proper credits in the near future.
Anyone feel free to compile a better structured how-to with correct references and credits.
Quick credits/thanks:
seanzscreams
untermensch
Stuff needed:
- Asus kernel source (10_4_2_9_kernel.zip)
- Android NDK R8B (I'm using Linux version, android-ndk-r8b-linux-x86.tar.bz2)
- Asu-JellyBean-HYDROKernel.zip (to get a proper update package structure with update binary/script and META-INF directory)
- signing-tools.zip, BlobTools and re/unpack-bootimg.pl (can't remember where I found these
will have to update post later...)
Preparations:
- Unpack kernel source, e.g. to $HOME/TF300/stock_kernel
- Unpack Android NDK, e.g. to $HOME/android-ndk-r8b
- Unzip Asu-JellyBean-HYDROKernel.zip, e.g. to $HOME/my_kernel
- Setup/install BlobTools and the other scripts
Step-by-step instructions:
1. Build kernel (zImage)
a) Fix minor issue in kernel source
> cd $HOME/TF300/stock_kernel
Change line 11 in file drivers/ril/ril.c
from,
#include <../../arch/arm/mach-tegra/include/mach/board-cardhu-misc.h>
to,
#include "../../arch/arm/mach-tegra/include/mach/board-cardhu-misc.h"
b) Setup build environment for cross compilation
> export PATH=$HOME/android-ndk-r8b/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86/bin:$PATH
> export ARCH=arm
> export CROSS_COMPILE=arm-linux-androideabi-
c) Fetch /proc/config.gz from your TF300 and copy/gunzip to $HOME/TF300/stock_kernel/.config
d) Build
> make
If everything went fine you should have a new kernel under,
$HOME/TF300/stock_kernel/arch/arm/boot/zImage
2. Repack kernel
> cd $HOME/my_kernel
a) Create a 28 byte file using a hex editor for the signblob header (I named the file signblob_magic)
It should have the following contents when checked with hexdump:
> hexdump -C signblob_magic
00000000 2d 53 49 47 4e 45 44 2d 42 59 2d 53 49 47 4e 42 |-SIGNED-BY-SIGNB|
00000010 4c 4f 42 2d 00 00 00 00 00 00 00 00 |LOB-........|
0000001c
b) Unpack the boot.blob from Asu-JellyBean-HYDROKernel.zip (unzipped earlier under Preparations)
This step is just to get a proper blob directory structure and the initramfs.
> blobunpack boot.blob
> unpack-bootimg.pl boot.blob.lnx
c) Pack new kernel
Might as well post the script I made to perform this task, check comments.
#!/bin/sh
SRC_HOME=$HOME/TF300/stock_kernel
KERNEL_NAME=my_kernel
# replace kernel
cp ${SRC_HOME}/arch/arm/boot/zImage boot.blob.lnx-kernel.gz
# repack
repack-bootimg.pl boot.blob.lnx-kernel.gz boot.blob.lnx-ramdisk out.blob.lnx
blobpack out.blob LNX out.blob.lnx
# add signblob header
cat signblob_magic out.blob > boot.blob
# create zip package
zip -9 -r ${KERNEL_NAME}.zip boot.blob META-INF/
# Sign zip package using SignApk
java -Xmx1024m -jar signapk.jar -w testkey.x509.pem testkey.pk8 ${KERNEL_NAME}.zip ${KERNEL_NAME}-signed.zip
3. Flash kernel
From previous steps you should now have a signed kernel called,
my_kernel-signed.zip
Flash it using TWRP and reboot.
If flash was OK a blue status bar should appear during boot and then your TF300 will reboot again.
Confirm you have a custom kernel by checking Kernel-version under Settings once system has completed the bootup.
