Note : This guide is outdated af. I'm planning to write a new guide at the end of the year 2024.

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

Screw APatch..🤡 Learn something new from here..❤️

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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.
• I'm not sure compiled kernels will work on MediaTek devices because their kernel sources are missing some drivers for MTK.
• Also, if you have a most recent Samsung device, building should be hard because of the new GKI kernels.

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

sudo apt update -y
sudo apt install default-jdk git gnupg flex bison gperf build-essential zip curl \
libc6-dev libncurses-dev libx11-dev libreadline-dev libgl1 libgl1-mesa-dev \
python3 make sudo gcc g++ bc grep tofrodos python3-markdown libxml2-utils xsltproc \
zlib1g-dev python-is-python3 libc6-dev libtinfo6 make repo cpio kmod openssl \
libelf-dev pahole libssl-dev -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..?

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✅ Downloading Part. (Only for samsung)

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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 :
  

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• ⚠️ 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).

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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

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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 ${ARGS} -j$(nproc) #to compile the kernel

#to copy all the kernel modules (.ko) to "modules" folder.
mkdir -p modules
find . -type f -name "*.ko" -exec cp -n {} modules \;
echo "Module files copied to the 'modules' folder."

• ❗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 ${ARGS} -j$(nproc) #to compile the kernel

#to copy all the kernel modules (.ko) to "modules" folder.
mkdir -p modules
find . -type f -name "*.ko" -exec cp -n {} modules \;
echo "Module files copied to the 'modules' folder."

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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

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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 .

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

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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".

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❗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..! 🧠

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

• Image :
  
  

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

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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 :
  
  

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✅ Compilation Process.

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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.

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Notes:

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

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

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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 :
  
  

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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".

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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 :
  
  

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