kernel-installation.sh

#!/usr/bin/env bash
set -e
source /etc/os-release

if [ "${ID}" = "ubuntu" ] ; then
    echo "Ubuntu - Install kernel"
    # Download mainline kernel packages, kernel up to 5.13 available in ubuntu 20.04 and 22.04 have a broken NAT implementation.
    cd /tmp
    wget --no-directories \
         --no-parent \
         --accept-regex generic \
         --recursive \
         --execute robots=off \
        https://kernel.ubuntu.com/mainline/${UBUNTU_MAINLINE_KERNEL_VERSION}/amd64/

    apt-get install --yes \
        /tmp/linux-image* \
        /tmp/linux-modules* \
        cpufrequtils \
        intel-microcode
else
    echo "Debian - Install kernel"

    cat <<EOF > /etc/apt/sources.list
deb http://deb.debian.org/debian trixie main contrib non-free-firmware
deb http://deb.debian.org/debian trixie-updates main contrib non-free-firmware
deb http://security.debian.org/debian-security trixie-security main contrib non-free-firmware
EOF

    apt update && apt install -y intel-microcode linux-image-${KERNEL_VERSION}-amd64 linux-cpupower
fi

# Remove WIFI, netronome, v4l and liquidio firmware to save ~300MB image size
rm -rf /usr/lib/firmware/*wifi* \
    /usr/lib/firmware/amd* \
    /usr/lib/firmware/liquidio \
    /usr/lib/firmware/mrvl \
    /usr/lib/firmware/netronome \
    /usr/lib/firmware/qcom \
    /usr/lib/firmware/v4l* \
    /var/lib/apt/lists/* \
    /tmp/*