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Environment Setup

Repository Setup

1. Create a GitHub repository to which you want to import the Linux kernel source. (e.g., https://github.com/kyungjae-lee/linux-kernel-v6.4.2.git)

2. Clone the Linux kernel source repository to your local machine.

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   git clone --depth=1 --branch v6.4.2 <source_repository_url> <local_directory>
   

   The last argument specifies the name of the local directory into which the Linux kernel source will be cloned.

3. Move into the local directory

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   cd <local_directory>
   

4. Remove the .git directory.

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   rm -rf .git/
   

5. Restructure your local directory according to your needs. (I've moved the entire source tree into a newly created subdirectory named linux.)

6. Convert the local directory to a Git repository.

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   git init
   

7. Create a new remote called origin located at your GitHub repository.

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   git remote add origin <your_repository_url>
   

   Once you do this, in your push commands, you can push to origin instead of typing out the whole URL.

8. Add the change in the working directory to the staging area.

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   git add .
   

9. Perform the initial commit.

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   git commit -m "Initial commit"
   

10. Push your local changes to your online repository.

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    git push -u origin main
    

Build Tool Installation

• Install the tools necessary for kernel compilation/build.

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  sudo apt install -y gcc-aarch64-linux-gnu g++-aarch64-linux-gnu \
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      cscope libssl-dev libncurses-dev\
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      autoconf automake autotools-dev curl libmpc-dev libmpfr-dev \
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      libgmp-dev gawk build-essential bison flex texinfo \
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      gperf libtool patchutils bc zlib1g-dev libexpat-dev
  

• Please see https://www.kernel.org/doc/html/latest/process/changes.html for more details.

Kernel Build (Cross-Compilation)

Using a Shell Script

1. Create a shell script in the root path of the local directory.

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   #!/bin/bash
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   # Shell script is to configure the build environment and initiate the process of building
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   # the Linux kernel for the ARM64 architecture using the "aarch64-linux-gnu-" cross-compiler
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   # Get the path of the directory containing the script (current working directory)
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   ROOT_DIR="$( cd "$(dirname "$0")" ; pwd -P )"
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   # Create the "out" directory to store build output
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   OUT_DIR="$ROOT_DIR/out"
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   echo "$OUT_DIR"
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   # Define variables for the kernel name and the build log file path
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   BUILD_LOG="$ROOT_DIR/build_log.txt"
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   # Move into the "linux" directory where the kernel source is located
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   cd linux
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   # Clean up any leftover files from previous kernel builds in your source directory
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   make mrproper
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   # Create a default configuration for building the Linux kernel targeting the "ARM64" architecture
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   # using the "aarch64-linux-gnu-" cross-compiler
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   make O=$OUT_DIR ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig
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   # Do additional configurations (Optional; Uncomment the follwoing command if necessary)
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   # This command opens an interactive menu that allows you to customize the configuration settings
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   # for building the Linux kernel targeting the "ARM64" architecture using the specified 
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   # cross-compiler (`aarch64-linux-gnu-`).
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   #make O=$OUTPUT ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- menuconfig
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   # Start the kernel build process for the "ARM64" architecture using the specified cross-compiler,
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   # utilizing multiple cores (parallel compilation) to speed up the build process.
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   # 2>&1 | tee $BUILD_LOG: Redirect both standard output and standard error to the $BUILD_LOG file,
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   # while also printing them to the terminal.
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   make O=$OUT_DIR ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j$(nproc) 2>&1 | tee $BUILD_LOG
   

2. Give the shell script execute permission.

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   sudo chmod +x build_kernel_aarch64.sh
   

3. Run the shell script.

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   sudo ./build_kernel_aarch64.sh
   

   When the build is complete, vmlinux will be created in out/, and Image will be generated in out/arch/arm64/boot/.