[GUIDE][TOOL] How Build/Compile your own kernel for LG G2 - G2 General

There is still no "how to" specific to the LG G2, so I'll try to share the maximum of my experience (or almost) with ["kernel", "build", "LG G2"] here. I'll show two methods different using CM12 kernel, The method for LG ROMs is very similar, I show some tips for LG ROMs also. The first method is the "manual" and second is the "automatic" using my "tool" called DCC. So come on! For this you will need a computer running Linux (x64) and have knowledge about basic Linux commands. I'm using a laptop (i3-2328M and 4GB of RAM) running Ubuntu 14.10 :good:
Setting Up the Environment
First install the essential tools (common environment for those already working with C/C++):
Code:
sudo apt-get install bison build-essential curl flex git gnupg gperf libesd0-dev liblz4-tool libncurses5-dev libsdl1.2-dev libwxgtk2.8-dev libxml2 libxml2-utils lzop openjdk-7-jdk openjdk-7-jre pngcrush schedtool squashfs-tools xsltproc zip zlib1g-dev g++-multilib gcc-multilib lib32ncurses5-dev lib32readline-gplv2-dev lib32z1-dev
Check Java and Java Compiler version:
Code:
java -version && javac -version
If the default Java is 1.6.x, Use this command and select java-7-openjdk as default:
Code:
sudo update-alternatives --config java
Click to expand...
Click to collapse
Setting Up the kernel Environment
Code:
mkdir -p ~/android/mykernel && cd ~/android/mykernel && mkdir out
This will create a folder and two subfolder in your home, Within mykernel folder will get all the tools that we will set up. Now we set the toolchain, Particularly I use Linaro 4.9.3, the version optimized for Cortex-A15 by @Christopher83, so I will use it here.
Clone Linaro GCC 4.9.3:
Code:
git clone https://github.com/Christopher83/arm-cortex_a15-linux-gnueabihf-linaro_4.9
Now the required binaries (Common essential binaries to work with msm8974):
Code:
git clone https://github.com/ferreirawax/mkboot_exec ~/android/mykernel/executables
Clone the RAM disk compiled from CM12:
Code:
git clone -b aosp https://github.com/ferreirawax/ramdisk_g2 ~/android/mykernel/ramdisk
For stock Kitkat:
This RAM disk was extracted from my d805 (d805 is a d802 which was released in latin america), then so will work on the d802, d805 and d806 (d806 is a d802 as the d805) If the variant is another you will have to draw your own device using a tool such AIK or search repositories of other developers.
Click to expand...
Click to collapse
Code:
git clone -b lge https://github.com/ferreirawax/ramdisk_g2 ~/android/mykernel/ramdisk
Now finally the source code of the kernel, Here I will use a configured kernel to compile the code without CM12 source, you can use the source code that is in the official repositories of CM12, but you will face some errors and warnings during the build that can be solved using the commits that are in my source and supply of other developers.
Clone kernel source:
Code:
git clone -b cm-12.0 https://github.com/ferreirawax/kernel_lge_msm8974-patched ~/android/mykernel/msm8974
For stock KitKat:
Code:
git clone -b lge-kitkat https://github.com/ferreirawax/kernel_lge_msm8974-patched ~/android/mykernel/msm8974
Apparently not but we already have a complete environment, see the folders in mykernel to have a shadow on it. Now let's the good part of the story. :fingers-crossed:
Click to expand...
Click to collapse
Compiling
Enter in kernel folder:
Code:
cd msm8974
Export Architecture and Toolchain:
Code:
export ARCH=arm
export CROSS_COMPILE=~/android/mykernel/arm-cortex_a15-linux-gnueabihf-linaro_4.9/bin/arm-eabi-
For stock KitKat you need export LZ4 path:
Code:
export PATH=$PATH:tools/lz4demo
Select the model of the device you want to compile your pointing due defconfig, If you are using source code directly from the repositories of the CM12, defconfig each supported model is called "cyanogenmod_MODEL_defconfig".
Select model to build (In my case I will compile for d802):
Code:
make d802_defconfig
Now let's clear the specific waste of d802:
Code:
make clean && make mrproper
Select model again to generate new .config:
Code:
make d802_defconfig
Now we start to build:
Code:
make -j4
-j4 is suitable for dual-core processors and -j5 for quad-core.
Depending on the configuration of your PC can take up to 20 minutes. In my laptop the build time is about 10 minutes. If you are using VirtualBox, can take much longer. Upon completion, will generate a zImage and some dtb (Device tree binary) files, The dtb files will be used to create a specific image (dt.img) file containing board informations. Now let's create a RAM disk and then dt.img to later put it all together and result in a final boot.img.
Enter in executables folder:
Code:
cd ~/android/mykernel/executables
Create GNUZip compressed RAM disk:
Code:
./mkbootfs ~/android/mykernel/ramdisk | gzip > ~/android/mykernel/out/ramdisk.gz
Create dt.img:
First copy the dtc file that is in executables folder to /usr/bin
Code:
gksu nautilus
This will open the file manager with root privileges, After click the left mouse button and select the dtc as executable.
You may need to restart, After that create the dt.img with the following command.
Code:
./dtbTool -s 2048 -o ~/android/mykernel/out/dt.img ~/android/mykernel/msm8974/arch/arm/boot/
Finally assemble boot.img file:
Code:
./mkbootimg --kernel ~/android/mykernel/msm8974/arch/arm/boot/zImage --ramdisk ~/android/mykernel/out/ramdisk.gz --cmdline "XXXX" --base 0x00000000 --pagesize 2048 --offset 0x05000000 --tags-addr 0x04800000 --dt ~/android/mykernel/out/dt.img -o ~/android/mykernel/out/boot.img
Replace the XXXX for the following:
console=ttyHSL0,115200,n8 androidboot.hardware=g2 user_debug=31 msm_rtb.filter=0x0 mdss_mdp.panel=1:dsi:0:qcom,mdss_dsi_g2_lgd_cmd androidboot.selinux=permissive
Do not remove the quotes. Replace the panel model (red) for your model. if you are compiling for stock KitKat, remove everything that is green.
Click to expand...
Click to collapse
Now let's add a "signature" in your kernel for the damn locked LG G2 bootloader so you can not be invalidated. If you do not do this procedure, the bootloader of your LG G2 will verify that this kernel has a particular signature, as it does not have your device will be unable to boot. We have two tools for this, Loki is able to fool the bootloader and open_bump (This tool is controversy) is able to add a "valid" signature using illegal means. I'll show how to use both. To this is very simple..
open_bump method:
You need Python to run any Python code, open_bump requires Python 2.x
Code:
git clone https://github.com/CyboLabs/Open_Bump
cd Open_Bump && python open_bump.py ~/android/mykernel/out/boot.img
You will now have an output "boot_bumped.img".
loki_tool method:
First get a copy of the bootloader of your G2, For this you need the adb installed and your G2 properly connected to your PC.
Get bootloader:
Code:
sudo apt-get install android-tools-adb
adb devices && adb shell "su -c dd if=/dev/block/platform/msm_sdcc.1/by-name/aboot of=/sdcard/aboot.img"
adb pull /sdcard/aboot.img
Do not forget the USB debugging enabled
Patch kernel:
Code:
./loki_patch boot aboot.img ~/android/mykernel/out/boot.img ~/android/mykernel/out/loki_boot.img
Will generate an output "loki_boot.img" on mykernel/out folder.
You can install using "my easy installer" (Attached at the end of post):
Download the attachment and extracted, Place your boot.img in the delta folder and
copy all the modules that are in your kernel source for the modules folder:
Code:
find ~/android/mykernel/msm8974/. -name "*.ko" -type f -exec cp {} ~/android/mykernel/installer/system/lib/modules \;
Now zip folder and install on your device. This installer already have panel detection script by @dr87
{
"lightbox_close": "Close",
"lightbox_next": "Next",
"lightbox_previous": "Previous",
"lightbox_error": "The requested content cannot be loaded. Please try again later.",
"lightbox_start_slideshow": "Start slideshow",
"lightbox_stop_slideshow": "Stop slideshow",
"lightbox_full_screen": "Full screen",
"lightbox_thumbnails": "Thumbnails",
"lightbox_download": "Download",
"lightbox_share": "Share",
"lightbox_zoom": "Zoom",
"lightbox_new_window": "New window",
"lightbox_toggle_sidebar": "Toggle sidebar"
}
Finally now you have your own kernel! Now I will show the second method of how to automatic compile your kernel using my tool.
To rebuild you have to use the following:
Code:
make clean && make mrproper
make MODEL_defconfig
make -j4
Click to expand...
Click to collapse
Some tips
To not export the toolchain path every time you restart the system, Create a Shell executable in /etc/profile.d as follows:
Code:
sudo nano /etc/profile.d/export_gcc.sh
Copy and paste:
export PATH=~/android/mykernel/arm-cortex_a15-linux-gnueabihf-linaro_4.9/bin:$PATH
Click to expand...
Click to collapse
CTRL + X, Y, ENTER
Now you just use:
Code:
export ARCH=arm
export CROSS_COMPILE=arm-eabi-
Useful guides:
If you are new, you can start learning about git, One of the main tools for working with modifications to your kernel. Below I leave some links with some guides that can help you.
How to use Github
How to cherry-pick a github commit
Click to expand...
Click to collapse

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DCC is a tool I developed to simplify my day, DCC is just a simple Python code that can help you save your time! See the features:
Command-line arguments like M$'s DiskPart
Real-time Shell executer
Manage builds for AOSP and LG ROMs
Build for single or ALL variants in same time
Manage the parameters of your kernel
DCC works with embedded open_bump
Manage your favorite toolchain
Easy to configure and use
I'll show how to use DCC is easy
Setup kernel environment:
Code:
reset && cd $HOME
mkdir dev && cd dev
git clone https://github.com/ferreirawax/dcc
cd dcc && find . -name '.gitignore' -delete
git clone https://github.com/ferreirawax/ramdisk_g2_aosp ramdisk/aosp
git clone https://github.com/ferreirawax/kernel_lge_msm8974-patched msm8974/aosp
Build kernel:
Code:
python dcc.py
do boot d802
exit
You know what happens to these magical commands? An immediate flashable zip of your kernel ready to flash. But for that you need to "setup" to your taste, see the page on github.

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@ferreirawax this is great i was waiting for something like this so much, tommorow i will try your guide and post the results
EDIT
I followed everything and got stuck here:
[email protected]:~/android/mykernel/msm8974$ make clean && make mrproper
make: /home/simex/android/mykenel/arm-cortex_a15-linux-gnueabihf-linaro_4.9/bin/arm-eabi-gcc: Command not found
THANKS for help
EDIT 2
I tried method with DCC and im stuck here:
[email protected]:~/dev/dcc$ python dcc.py
Traceback (most recent call last):
File "dcc.py", line 19, in <module>
from colorama import *
ImportError: No module named colorama
[email protected]:~/dev/dcc$
Sorry if im annoying but i hope someone can help me

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Boris31 said:
@ferreirawax this is great i was waiting for something like this so much, tommorow i will try your guide and post the results
EDIT
I followed everything and got stuck here:
[email protected]:~/android/mykernel/msm8974$ make clean && make mrproper
make: /home/simex/android/mykenel/arm-cortex_a15-linux-gnueabihf-linaro_4.9/bin/arm-eabi-gcc: Command not found
THANKS for help
EDIT 2
I tried method with DCC and im stuck here:
[email protected]:~/dev/dcc$ python dcc.py
Traceback (most recent call last):
File "dcc.py", line 19, in <module>
from colorama import *
ImportError: No module named colorama
[email protected]:~/dev/dcc$
Sorry if im annoying but i hope someone can help me
Click to expand...
Click to collapse
This error happens when the toolchain path is wrong.
Colorama module need to use DCC (I forgot to mention that)
Code:
sudo pip install colorama

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Really exited to see sutch a complete guide for how to make a kernel for our G2
Will try and see if I can manager to compile my first kernel with this guide today..

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ferreirawax said:
This error happens when the toolchain path is wrong.
Colorama module need to use DCC (I forgot to mention that)
Code:
sudo pip install colorama
Click to expand...
Click to collapse
ok thanks i got i working
---------- Post added at 10:43 AM ---------- Previous post was at 10:21 AM --------- @ferreirawax you got a typing mistake here thats why method 1 didnt work i finaly figured it out:
Export Architecture and Toolchain:
Code:
export ARCH=arm
export CROSS_COMPILE=~/android/mykenel/arm-cortex_a15-linux-gnueabihf-linaro_4.9/bin/arm-eabi-
It should be myKERNEL and that it works
Now i succesfully build my kernel but im having problems with bump, i cant get past this:
[email protected]:~$ python open_bump.py ~/android/mykernel/out/boot.img
python: can't open file 'open_bump.py': [Errno 2] No such file or directory
but im sure its there i tryed nearly everything but cant get bumped boot.img

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Thank you!!!! I have wanted something like this to compile different kernels .

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It would have been totally awesome if @dorimanx did a tutorial once where he shared how he makes his (stock) kernels..anyways will this work on a 11 year old PC with 1gb RAM and 1,7 GHz processor?

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any help for bumping boot.img ?

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Boris31 said:
any help for bumping boot.img ?
Click to expand...
Click to collapse
http://forum.xda-developers.com/showthread.php?p=56987541
(OP gave cmd lines too)

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6ril1 said:
http://forum.xda-developers.com/showthread.php?p=56987541
(OP gave cmd lines too)
Click to expand...
Click to collapse
Yeah thanks i finally got it

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Norside said:
It would have been totally awesome if @dorimanx did a tutorial once where he shared how he makes his (stock) kernels..anyways will this work on a 11 year old PC with 1gb RAM and 1,7 GHz processor?
Click to expand...
Click to collapse
This is willpower

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Boris31 said:
Yeah thanks i finally got it
Click to expand...
Click to collapse
Now you have what start modifying your kernel!

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ferreirawax said:
Now you have what start modifying your kernel!
Click to expand...
Click to collapse
Yeah finally i'v built a kernel now i need to learn to modify it. Any good guide for that maybe

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Boris31 said:
Yeah finally i'v built a kernel now i need to learn to modify it. Any good guide for that maybe
Click to expand...
Click to collapse
For that you need to read a little about git, then see the changes made by other developers and place them in your own kernel.

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ferreirawax said:
For that you need to read a little about git, then see the changes made by other developers and place them in your own kernel.
Click to expand...
Click to collapse
Thanks, I'm finally beginning to understand Linux terminal commands.

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@ferreirawax
I am aware that the rules prohibit posting simple thanks but I feel duty do it here because it is really nice to find shared topics showing how to fish rather than giving fish.
Big thank you to you so, great initiative !

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@ferreirawax
Thanks for taking the time to post this. I would love for more people to try their hand at Custom Kernels! Otherwise you end up with the same kernel, different name.

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DTB combiner:
Input directory: '/home/bolt890/dev/dcc/msm8974/aosp/arch/arm/boot/'
Output file: '/home/bolt890/dev/dcc/outputs/dt.img'
Found file: msm8974-v2-2-g2-open_com.dtb ... skip, failed to scan for 'qcom,msm-id = <' tag
Found file: msm8974-v2-g2-open_com.dtb ... skip, failed to scan for 'qcom,msm-id = <' tag
Found file: msm8974-g2-open_com.dtb ... skip, failed to scan for 'qcom,msm-id = <' tag
=> Found 0 unique DTB(s)
error: dt.img not found, failed to make target
Keep getting this error

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bolt890 said:
DTB combiner:
Input directory: '/home/bolt890/dev/dcc/msm8974/aosp/arch/arm/boot/'
Output file: '/home/bolt890/dev/dcc/outputs/dt.img'
Found file: msm8974-v2-2-g2-open_com.dtb ... skip, failed to scan for 'qcom,msm-id = <' tag
Found file: msm8974-v2-g2-open_com.dtb ... skip, failed to scan for 'qcom,msm-id = <' tag
Found file: msm8974-g2-open_com.dtb ... skip, failed to scan for 'qcom,msm-id = <' tag
=> Found 0 unique DTB(s)
error: dt.img not found, failed to make target
Keep getting this error
Click to expand...
Click to collapse
Seem to lack the DTC binary on your system. Download the attachment and follow:
Code:
sudo cp ~/dtc.zip /usr/bin/dtc
Or you can simply remove the extension and copy the file to /usr/bin any other way, may be necessary to a log-in/out for effect. Then compile again.