build-kernel

#!/bin/bash
# shellcheck disable=SC2016,SC2046,SC2066,SC2068,SC2086,SC2162,SC2317

clear

###########################################################################################################
##
##  GitHub: https://github.com/slyfox1186/Windows-WSL2-Kernel-build-script
##
##  Supported Distros: Debian-based ( Debian, Ubuntu, etc. )
##
##  Supported architecture: x86_x64
##
##  Purpose: Build the latest Microsoft WSL2 kernel release to link to your current distros.
##
##  Install info: The new kernel will be located in the root build directory; the filename will be: vmlinux
##
##                Place vmlinux into a folder inside your Windows "%USERPROFILE%" folder.
##                I placed mine into the folder I created called: "%USERPROFILE%\WSL2\vmlinux"
##
##                Create a file called "%USERPROFILE%\.wslconfig" and visit the below website for
##                instructions on how to link the new kernel to your linux distros.
##
##                https://learn.microsoft.com/en-us/windows/wsl/wsl-config
##
##  Updated: 04.19.23
##
##  Version: 1.0
##
###########################################################################################################

##
## define variables
##

script_ver='1.0'

##
## set the available cpu thread and core count for parallel processing (speeds up the build process)
##

if [ -f '/proc/cpuinfo' ]; then
    cpu_threads="$(grep -c ^processor '/proc/cpuinfo')"
else
    cpu_threads="$(nproc --all)"
fi
cpu_cores="$(grep ^cpu\\scores '/proc/cpuinfo' | uniq | awk '{print $4}')"

##
## define functions
##

exit_fn()
{
    echo
    echo 'The new kernel will be located in the root build directory'
    echo
    echo 'The filename will be called: vmlinux'
    echo
    echo 'Place the kernel into a folder inside your "%USERPROFILE%"'
    echo
    echo 'I placed mine into the folder I created called: "%USERPROFILE%\WSL2\vmlinux"'
    echo
    echo 'Create a file called "%USERPROFILE%\.wslconfig" and look up online how to link'
    echo 'the new kernel you copied so that your WSL2 linux Distro loads it.'
    echo
    echo 'Make sure to star this repository to show your support!'
    echo
    echo 'https://github.com/slyfox1186/Windows-WSL2-Kernel-build-script/'
    echo
    exit 0
}

fail_fn()
{
    echo
    echo "$1"
    echo
    echo 'Please create a support ticket'
    echo
    echo 'https://github.com/slyfox1186/Windows-WSL2-Kernel-build-script/issues/'
    echo
    exit 1
}

cleanup_fn()
{
    echo '=========================================='
    echo ' Do you want to clean up the build files? '
    echo '=========================================='
    echo
    echo '[1] Yes'
    echo '[2] No'
    echo
    read -p 'Your choices are (1 or 2): ' cleanup_ans

    if [ "$cleanup_ans" -eq '1' ]; then
        remove_file "$0"
        echo 'cleanup finished.'
        exit_fn
    elif [ "$cleanup_ans" -eq '2' ]; then
        exit_fn
    else
        echo 'Bad user input'
        echo
        read -p 'Press enter to try again.'
        clear
        cleanup_fn
    fi
}

make_dir()
{
    remove_dir "$1"
    if ! mkdir "$1"; then
        printf "\n Failed to create dir %s" "$1"
        echo
        exit 1
    fi
}

remove_file()
{
    if [ -f "$1" ]; then
        sudo rm -f "$1"
    fi
}

remove_dir()
{
    if [ -d "$1" ]; then
        sudo rm -fr "$1"
    fi
}

download()
{
    dl_path="$PWD"
    dl_file="${2:-"${1##*/}"}"

    if [[ "$dl_file" =~ tar. ]]; then
        target_dir="${dl_file%.*}"
        target_dir="${3:-"${target_dir%.*}"}"
    else
        target_dir="${3:-"${dl_file%.*}"}"
    fi

    if [ ! -f "$dl_path/$dl_file" ]; then
        echo "Downloading $1 as $dl_file"
        if ! curl -Lso "$dl_path/$dl_file" "$1"; then
            echo
            echo "The script failed to download \"$1\" and will try again in 10 seconds"
            sleep 10
            echo
            if ! curl -Lso "$dl_path/$dl_file" "$1"; then
                echo
                echo "The script failed to download \"$1\" two times and will exit the build"
                echo
                fail_fn
            fi
        fi
        echo 'Download Completed'
        echo
    else
        echo "$dl_file is already downloaded"
    fi

    make_dir "$dl_path/$target_dir"

    if [ -n "$3" ]; then
        if ! tar -xf "$dl_path/$dl_file" -C "$dl_path/$target_dir" &>/dev/null; then
            fail_fn "Failed to extract $dl_file"
        fi
    else
        if ! tar -xf "$dl_path/$dl_file" -C "$dl_path/$target_dir" --strip-components 1 &>/dev/null; then
            fail_fn "Failed to extract $dl_file"
        fi
    fi

    echo "File extracted: $dl_file"

    cd "$dl_path/$target_dir" || fail_fn "Unable to change the working directory to $target_dir"
}

execute()
{
    echo "$ $*"

    if ! output=$("$@" 2>&1); then
        fail_fn "Failed to Execute $*"
    fi
}

build()
{
    echo
    echo "building $1 - version $2"
    echo '===================================='

    if [ -f "$PWD/$1.done" ]; then
        if grep -Fx "$2" "$PWD/$1.done" 2>/dev/null; then
            echo "$1 version $2 already built. Remove $PWD/$1.done lockfile to rebuild it."
            return 1
        elif $latest; then
            echo "$1 is outdated and will be rebuilt using version $2"
            return 0
        else
            echo "$1 is outdated, but will not be rebuilt. Pass in --latest to rebuild it or remove $PWD/$1.done lockfile."
            return 1
        fi
    fi

    return 0
}

build_done() { echo "$2" > "$PWD/$1.done"; }

installed() { return $(dpkg-query -W -f '${Status}\n' "$1" 2>&1 | awk '/ok installed/{print 0;exit}{print 1}'); }

clear
echo "WSL2-Custom-Kernel build script v$script_ver"
echo '======================================'

echo
echo "The script will utilize ( $cpu_threads cpu cores ) for parallel processing to accelerate the build speed."

##
## required apt packages
##

build_pkgs_fn()
{
    echo
    echo 'Installing required apt packages'
    echo '=================================='

    pkgs=(build-essential curl flex bison dwarves gcc g++ gcc-12 g++-12 jq libssl-dev libelf-dev bc)

    for pkg in ${pkgs[@]}
    do
        if ! installed "$pkg"; then
            missing_pkgs+=" $pkg"
        fi
    done

    if [ -n "$missing_pkgs" ]; then
        for pkg in "$missing_pkgs"
        do
            if sudo apt -y install $pkg; then
                echo
                echo 'The required apt packages were installed.'
                echo
            else
                fail_fn 'The required apt packages failed to install'
            fi
        done
        echo 'The required apt packages are already installed.'
    fi
}

# install required apt packages
build_pkgs_fn

VERSION=6.6.36.6

if build 'wsl2-linux-kernel' "linux-msft-wsl-${VERSION}"; then
    download "https://api.github.com/repos/microsoft/WSL2-Linux-Kernel/tarball/linux-msft-wsl-${VERSION}" "linux-msft-wsl-${VERSION}.tar.gz"
    echo 'yes' | make KCONFIG_CONFIG=../config-wsl -j "$cpu_cores"
    build_done 'wsl2-linux-kernel' "linux-msft-wsl-${VERSION}"
fi

exit_fn