/Android-Kernel-Tutorials

Kernel building tutorials for Any device which is currently unsupported with APatch.

GNU General Public License v3.0GPL-3.0

How to Compile the Kernel for APatch for Unsupported Devices..?

What You'll Need: A Working 🧠, PC/RDP with any Linux GUI distro, Knowledge of basic commands in Linux, Understanding of English.

Additional Notes:

  • If you're feeling a bit lazy to install a Linux distro, you can also use Gitpod. Keep in mind, though, it might be more challenging.

Requirements for compiling kernels : (Paste this in terminal.)

sudo apt update -y
sudo apt install default-jdk git-core gnupg flex bison gperf build-essential zip curl libc6-dev libncurses5-dev x11proto-core-dev libx11-dev libreadline6-dev libgl1-mesa-glx libgl1-mesa-dev python3 make sudo gcc g++ bc grep tofrodos python3-markdown libxml2-utils xsltproc zlib1g-dev libncurses5 python-is-python3 libc6-dev libtinfo5 ncurses-dev make python2 repo cpio kmod openssl -y


❗The video Guide for this tutorial can be found here : Open in YouTube

Quick Links :

  1. ✅ Downloading Part. (Only for samsung)
  2. ✅ Compiling Part (Universal for any device).
  3. ✅ (❗ Samsung Specific) How to disable kernel securities from the menuconfig..?
  4. ✅ How to make your kernel supports with APatch..?
  5. ✅ Compilation Process.
  6. ✅ (FINAL) How to put the compiled kernel, inside our boot.img..?

✅ Downloading Part. (Only for samsung)

01. Download the kernel source from the Samsung Opensource.

02. Extract the Kernel.tar.gz from the source zip, unarchive it using this command.

tar xvf Kernel.tar.gz; rm Kernel.tar.gz

Additional note : If your Kernel source's folders are locked like this, you can change the entire folder's permissions to read and write.

  • Problem :
  • Solution :
  • ⚠️ For other devices, You can find them by your OEM's sites or from your OEM's official GitHub repos.

✅ Compiling Part (Universal for any device).

01. After downloading or cloning the Kernel Source, We must make a Script to compile our kernel.

  • Before making a build script, we must download compilers to build the kernel.
  • if you own a Snapdragon/Mediatek device, I recommend you to use Google's Compilers.
  • You can clone them using this command : (❗only for every Snapdragon/Mediatek devices from any OEM)
cd ~
git clone https://github.com/ravindu644/Toolchains_by_Google.git
  • Or, If you prefer Qualcomm's own compilers rather than Google's, you can clone them using this command :
cd ~
git clone https://github.com/ravindu644/Toolchains_for_Snapdragon.git
  • Or, If you prefer Proton clang to compile the kernel (Qualcomm and Mediatek), Jump to this Guide : Click here

Notes : (Samsung exynos specific) If your device is exynos, Open the "README_Kernel.txt" and download the toolchains by Googling the values for "CC" and "CROSS_COMPILE". You can find them easily from the Google Opensource or github.

  • For an Example :

  • Now, Open the terminal from your Kernel source's folder and create a new file called build.sh using this command :

touch build.sh
  • Open the newly created build.sh and make that file looks like this : (⚠️ This code is only for Snapdragon and Mediatek devices and not for Exynos)
  • The reason for that is, Snapdragon and Mediatek kernel sources only supported to compile to a seperated directory called "out".
  • Here's the code : ⬇️
#!/bin/bash
clear
export ARCH=arm64
export PLATFORM_VERSION=13
export ANDROID_MAJOR_VERSION=t
ln -s /usr/bin/python2.7 $HOME/python
export PATH=$HOME/:$PATH
mkdir out

ARGS='
CC=$HOME/Toolchains_by_Google/clang-10.0/bin/clang
CROSS_COMPILE=$HOME/Toolchains_by_Google/aarch64-4.9/bin/aarch64-linux-android-
CLANG_TRIPLE=aarch64-linux-gnu-
ARCH=arm64
'
make -C $(pwd) O=$(pwd)/out ${ARGS} clean && make -C $(pwd) O=$(pwd)/out ${ARGS} mrproper #to clean the source
make -C $(pwd) O=$(pwd)/out ${ARGS} YOUR_DEFCONFIG #making your current kernel config
make -C $(pwd) O=$(pwd)/out ${ARGS} menuconfig #editing the kernel config via gui
make -C $(pwd) O=$(pwd)/out ${ARGS} -j16 #to compile the kernel
  • ❗If your Device is Samsung Exynos, It does't supports the compiling kernel in a separate directory. So, the code must be like this :
#!/bin/bash
clear
export ARCH=arm64
export PLATFORM_VERSION=13
export ANDROID_MAJOR_VERSION=t
ln -s /usr/bin/python2.7 $HOME/python
export PATH=$HOME/:$PATH

ARGS='
CC=$HOME/path/to/clang/bin/clang
CROSS_COMPILE=$HOME/path/to/gcc/bin/aarch64-linux-android-
CLANG_TRIPLE=aarch64-linux-gnu-
ARCH=arm64
'

make ${ARGS} clean && make ${ARGS} mrproper #to clean the source
make ${ARGS} YOUR_DEFCONFIG #making your current kernel config
make ${ARGS} menuconfig #editing the kernel config via gui
make ${ARGS} -j16 #to compile the kernel

Notes :

  • Edit the PLATFORM_VERSION value to your Android version.
  • Edit the ANDROID_MAJOR_VERSION value to your Android version's codename.
  • Edit CC value with the path to the clang's [bin folder]/clang.
  • Edit CROSS_COMPILE value with the path to the GCC's [bin folder]/aarch64-linux-android-
  • Replace YOUR_DEFCONFIG to your current defconfig which is located in arch/arm64/configs.

02. Edit the Makefile.

  • if you found these variables : CROSS_COMPILE, REAL_CC or CC, CFP_CC in your "makefile" ; remove them from the "Makefile"
  • search "wrapper" in your makefile. If there's a line related to a python file, remove that entire line/function too.
  • Search CONFIG_CC_STACKPROTECTOR_STRONG and replace it with CONFIG_CC_STACKPROTECTOR_NONE

Our build script must looks like this, after making the changes: (This is an example.)

03.❗ Bug fixing in the Kernel Source. (These are the universal errors for all the snapdragon kernel sources)

  • To fix the "symbol versioning failure for gsi_write_channel_scratch" error : Click here
  • Also, you will faced an error called scripts/gcc-version.sh: line 25: aarch64-linux-gnu-gcc: command not found if you used the Google's compilers, You can fix them too using this commit : Click here
  • To force load the vendor modules in some devices (Universal) ⚠️ (This fixes various hardware related issues after installing a custom kernel) - Click here

Now we finished setting up the basic configurations for kernel compilation.

04. Now, grant the executable permissions to build.sh using this command.

chmod +x build.sh

05. Finally, run the build script using this command :

./build.sh

After a couple of seconds, the "menuconfig" should appear.

  • Additional notes : Press space bar to enable/disable or enable as a module .

✅ (❗ Samsung Specific) How to disable kernel securities from the menuconfig..?

01. → Kernel Features => Disable "Enable RKP (Realtime Kernel Protection) UH feature", "Enable LKM authentication by micro hypervisor", "Block LKM by micro hypervisor", "Enable micro hypervisor feature of Samsung" respectively.

  • Image :

02. → Kernel Features → Control Flow Protection => Disable "JOP Prevention", "ROP Prevention" and "JOPP and ROPP" Respectively.

  • Image :

Additional notes :

  • If you can't find them (01 and 02) in the "→ Kernel Features", they are located in the "→ Boot options".

❗In Android 14 and some Android 13 sources, they are located in → Hypervisor. Disable them ALL!

  • Image :

  • As I mentioned at the beginning of this guide, your must use your brain..! 🧠

03. → Security options => Disable "Integrity subsystem" and "Defex Support".

  • Image :

✅ How to make your kernel supports with APatch..?

01. Open → General setup → Local version - append to kernel release => Choose any string you like.

  • Image :

02. Open → Kernel hacking => Turn on the Kernel debugging ❗.

  • Image :

03. → General setup → Configure standard kernel features (expert users) => Enable everything except "sgetmask/ssetmask syscalls support and Sysctl syscall support"

  • Image :

04. → Enable loadable module support => Enable "Forced module loading", "Module unloading", "Forced module unloading", "Module versioning support" and disable others.

  • Image :



    ❗Additional Notes : To force load the vendor/system modules in some devices, use this commit (⚠️ This fixes various hardware related issues after installing a custom kernel) - Click here

05. → Boot options => enable "Build a concatenated Image.gz/dtb by default" and "Kernel compression method (Build compressed kernel image)" ---> "(X) Build compressed kernel image"

  • Image :

06. → File systems => Enable "<*> Overlay filesystem support".

  • Image :

✅ Compilation Process.

07. Exit and Save the config.

  • When you see "configuration written", stop the compilation process with Ctrl+C and replace the content of ".config" with your desired defconfig.

08. Compile using ./build.sh --> Skip the menuconfig and wait until the compilation finishes..!

  • ℹ️ The compiled kernel will be located at out/arch/arm64/boot.

Notes:

  • If you encounter errors during the compilation process, it's advisable to search for these errors on GitHub and find a solution.

✅ (FINAL) How to put the compiled kernel, inside our boot.img..?

01. Extract the boot.img from the stock ROM/ROM ZIP. If you are a Samsung user, I prefer https://github.com/ravindu644/Scamsung to do this online.

- Use exact build number to download the firmware.

02. Unpack the boot.img using AIK-Linux which can be found in here : https://github.com/ravindu644/AIK-Linux

  • Image :

How to check "Which kernel format should I use"..?

  • Kernel without GZIP compression :

  • Kernel with GZIP compression :



Notes :

  • If your split_img has a boot.img-dtb + Uncompressed Kernel => Use "Image".
  • If your split_img has a boot.img-dtb + GZIP compressed Kernel => Use "Image.gz".
  • If your split_img don't has a boot.img-dtb + uncompressed Kernel => Use "Image-dtb". (if your out/arm64/boot folder don't have such a file, use Image instead)
  • If your split_img don't has a boot.img-dtb + GZIP compressed Kernel => Use "Image.gz-dtb".

03. Choose the required kernel as I mentioned above > Rename it to "boot.img-kernel" and copy and replace it with the boot.img-kernel, which is in the split_img folder.

04. Repack --> rename "image-new.img" to "boot.img" and make a tar file using this command :

tar cvf "DEVICE NAME (APatch Support).tar" boot.img

05. Flash it using Fastboot/ODIN..!

06. DONE..!

  • Proof :

Written by @Ravindu_Deshan for @SamsungTweaks and @APatchChannel | Sharing this without proper credit is not allowed..❗