How to extract the boot image from your tablet, set up adb, compile a new kernel with cool options, and put it back on your device!
UPDATED for Lolipop 12-4-14
This is a complete guide from start to finish, copy and paste style. If you own a gpe510, or any other AOSP device and a computer running Debian Linux, you can do all of this.
If all you want is the modified kernel, download from here:
Sleekai Kernel For The LG GPad 8.3 V510(GPE)
I am hoping people will add to this with new ideas and patches in order to make the GPE a better device. I see the potential for all sorts of neat stuff.
This guide assumes a basic knowledge of linux operating systems. I am using a Debian 64 bit (wheezy stable) to compile my kernel. I have used many, many hours of the day to figure this out properly, with specific thanks going to Pete of Pete's Blog for his image tools.
But first, lets keep this simple. As usual, you are on your own if you brick your device, though I don't see how you could if you are paying attention!
There are dependencies for building your own kernel, and you will definitely want to use a 64 bit system as a 32 bit will not work properly for kitkat.
Here are all of the packages you will need, and they will draw in further dependencies when you install, but these are it! So, here we go:
Open a terminal, su to root and:
Code:
dpkg --add-architecture i386
Code:
apt-get update ; apt-get install libc6:i386 libncurses5:i386 libstdc++6:i386 libc6-i686:i386 lzop liblzo2-dev libgpm2:i386 git-core git gnupg flex bison gperf libsdl1.2-dev libesd0-dev build-essential zip curl gedit libncurses5-dev zlib1g-dev fakeroot lib32z1-dev lib32ncurses5-dev gcc-multilib g++-multilib
Next, you will need to install adb and have your permissions set up.
In order to do this you will need to go into the developer options on your device to enable debugging on your tablet. Go to settings/about tablet/build number, and tap on build number several times to unlock the developer options.
then:
You will need to create new udev rules for your device in/etc/udev/rules.d on your computer.
Use "lsusb" in your terminal to find the manufactures code of your device. it will show up as a nexus 4, or Google device.
You will need to create a file in your computer in /etc/udev/rules.d/99-android.rules.
You can use gedit if you like:
Code:
gedit /etc/udev/rules.d/99-android.rules
Code:
# Google Nexus devices
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", MODE="0666", OWNER="your-login" # Google Nexus devices
You will then want to restart udev on your computer:
Code:
service udev restart
Now to download adb and get started. You should probably not use adb from the Debian repositories, as it may be an older version. the V510 is using kitkat android and needs the latest build of adb to work properly. It is a good idea to get rid of any old adb files on your computer first. The code below will do just that.
Code:
apt-get purge android-tools-adb android-tools-fastboot
Now download the latest adb bundle from here:
http://developer.android.com/sdk/index.html
Move it into a new directory,
*note -the version number may be different.
Code:
mkdir ~/adb
Code:
cd ~/adb
Code:
unzip adt-bundle-linux-x86_64-20131030.zip
Code:
mv adt-bundle-linux-x86_64-20131030 /opt/android-sdk-linux-x86_64-20131030
Next we need to link adb to /usr/bin
Code:
ln -s /opt/android-sdk-linux-x86_64-20131030/sdk/platform-tools/adb /usr/bin
Code:
ln -s /opt/android-sdk-linux-x86_64-20131030/sdk/platform-tools/fastboot /usr/bin
Code:
adb start-server
Code:
adb devices
Okay, wev'e got this first part set up. it's time to begin working on a kernel!
Lets get started.
I want to extract and build my zimage in $userspace, so open a terminal from /home and:
Code:
mkdir ~/android
https://www.lg.com/global/support/opensource/opensourceList?types=ALL&search=lgv510
and open it to find three folders, including a kernel folder. Move the kernel folder to ~/android and then:
Code:
cd ~/android
Code:
git clone https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-eabi-4.8
When it completes, enter ~/android/kernel and get ready to compile a new kernel from the source code.
Code:
cd ~/android/kernel
Code:
export PATH=$PATH:~/android/arm-eabi-4.8/bin
Code:
arm-eabi-gcc --version
Code:
arm-eabi-gcc (GCC) 4.6.x-google 20120106 (prerelease)
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Code:
export ARCH=arm
Code:
export SUBARCH=arm
Code:
export CROSS_COMPILE=arm-eabi-
Code:
export KERNEL_DEFCONFIG=palman_defconfig
Code:
make clean
Code:
make palman_defconfig
But for now,
Code:
make menuconfig
After saving your changes,
Code:
make
Code:
make -o2
and go make a pot of coffee, and probably drink the whole pot! This will take a while.
At the end you will see that the "zimage is ready"
If you have errors, then you probably have dependency problems. If not, Yay! You compiled your first kernel, but we are not done yet!
The zimage you just produced is stored in /kernel/arch/arm/boot/zImage
To put both the zimage and any modules into a separate folder inside of ~/android so as to make extracting them easier:
Code:
mkdir ~/android/kernel_output
Code:
cp ~/android/kernel/arch/arm/boot/zImage ~/android/kernel_output/zImage
Code:
find ~/android/kernel -name "*.ko" -exec cp {} ~/android/kernel_output/ \;
Extract your boot image (boot.emmc.win) for the ramdisk You may also download the stock.zip from the sleekai kernel thread
Now make a backup to transfer to your computer.
Reboot to recovery on your tablet. I'm using TWRP. If you are using something else it should be just as easy.
Code:
adb reboot recovery
make a backup to your sd card. I changed the name to boot.bac to keep it simple
reboot
make sure the backup of boot is present using a file explorer. I am using ES File explorer.
On your computer, pull the file using adb
Code:
adb start-server
Code:
adb devices
Code:
adb pull /storage/sdcard1/TWRP/BACKUPS/LG0000606708987/boot.bac /home/sleek
What we are after is the "boot.emmc.win" file. We will only need this and the zImage to compile a new boot image and run it on your tablet.
The tools to extract the kernel and ramdisk from the boot.emmc.win you will need the following boot image tools installed on your computer.
So, again, lets keep this simple. All the tools are forked to my github for ease of use.
So lets install the tools! Ready?
As Root:
Code:
mkdir /usr/src/android
Code:
mkdir /usr/src/android/boot
Code:
cd /usr/src/android/
Code:
git clone https://github.com/sleekmason/bootimg-tools.git
Code:
cd bootimg-tools/libmincrypt/
Code:
gcc -c *.c -I../include
Code:
ar rcs libmincrypt.a *.o
Code:
cd ../mkbootimg
Code:
gcc mkbootimg.c -o mkbootimg -I../include ../libmincrypt/libmincrypt.a
Code:
cp mkbootimg /usr/local/bin/
Code:
cd ../cpio
Code:
gcc mkbootfs.c -o mkbootfs -I../include
Code:
cp mkbootfs /usr/local/bin/
Code:
cd /usr/src/android/bootimg-tools/mkbootimg/
Code:
wget https://raw.github.com/sleekmason/bootimg-tools/master/mkbootimg/unmkbootimg.c
Code:
gcc -o unmkbootimg unmkbootimg.c
Code:
cp unmkbootimg /usr/local/bin/
Now everything is in place to make a new boot image for your tablet!
Finishing this up is easy.
As root, we made a directory in /usr/src/android/boot for your boot.emmc.win file to be torn apart:
Code:
cd /usr/src/android/boot
Note* "/home/sleek" is the path on my computer, and should be changed to reflect yours!
Code:
cp /home/sleek/android/kernel_output/zImage /usr/src/android/boot
Code:
cp /home/sleek/boot.emmc.win /usr/src/android/boot
Code:
unmkbootimg -i boot.emmc.win
Code:
rm boot.emmc.win kernel && mv zImage kernel
Code:
mkbootimg --base 0 --pagesize 2048 --kernel_offset 0x80208000 --ramdisk_offset 0x82200000 --second_offset 0x81100000 --tags_offset 0x80200100 --cmdline 'console=ttyHSL0,115200,n8 androidboot.hardware=palman lpj=67677 vmalloc=300M' --kernel kernel --ramdisk ramdisk.cpio.gz -o boot.emmc.win
Note* For 500 users this may be different. Simply use the command from the prompt.
You should now have a brand new boot.emmc.win image in /usr/src/android/boot!!
To push back on your device to test
Code:
adb reboot bootloader
Code:
fastboot boot boot.emmc.win
USING the above will only put your kernel build into memory and should not hurt your device if something goes wrong. Use the command below to make it permanent.
If everything works well, you should see the change you made to the /general/perf-localversion/ in your settings under kernel. from there it's up to you to hack away! make new and unique kernels!
If you want your kernel to survive reboot do;
Code:
fastboot flash boot boot.emmc.win
Code:
fastboot reboot
You can expect a slow bootup on the first go around as your new kernel populates the widgets, etc..
NOTE*For the use of the latest eabi-4.7 google toolchain, you will need the libglibc libraries from the "testing" branch as gcc 4.7 is in testing. I advise completing the guide with eabi 4.6 first before trying 4.7.
The gamma correction though enabled in 4.6, isn't near as good as the native compile using 4.7. If you want the screen to look like it does in my kernels, you will need 4.7
For the eabi-4.7:
Code:
git clone https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-eabi-4.7
That's it! Good luck! Remember, If you post a kernel you have made, you will need to show your kernel source, etc . . . Git hub is a good choice to keep track of changes you make. Best regards, Sleekmason
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