Script to force Ubuntu 21.04 to use kernel version 5.10

hirsute-510-kernel.sh

#!/bin/bash -e

# You will probably need to adjust this script if you aren't using
# the generic kernel.

to_install=
to_hold=
pd=/tmp/packages.$$
mkdir $pd

# Get good Kernel packages

while read package arch; do
    to_hold="$to_hold $package:$arch"
    if dpkg-query --show --showformat '${Package} ${Version} ${Status}\n' \
                  $package:$arch 2>/dev/null | grep -v deinstall |
            grep -q -s '5\.10\.0-14\.15 '
    then
        continue
    fi
    deb_name="${package}_5.10.0-14.15_${arch}.deb"
    echo Downloading $deb_name
    curl --location --silent --output $pd/$deb_name \
         "https://launchpad.net/ubuntu/+archive/primary/+files/$deb_name"
    to_install="$to_install $pd/$deb_name"
done < <(dpkg-query --show --showformat \
         '${Package} ${Architecture} ${Version} ${Source}\n' '*linux*' |
         awk '$4 == "linux" || $4 == "linux-signed" {print $1, $2}' |
         sed 's/-5\.[0-9.]*-[0-9]*/-5.10.0-14/' | sort -u)

# Get good Kernel meta-packages

while read package arch version; do
    to_hold="$to_hold $package:$arch"
    if [ "$version" == "5.10.0.14.16" ]; then
        continue
    fi
    deb_name="${package}_5.10.0.14.16_${arch}.deb"
    echo Downloading $deb_name
    curl --location --silent --output $pd/$deb_name \
         "https://launchpad.net/ubuntu/+archive/primary/+files/$deb_name"
    to_install="$to_install $pd/$deb_name"
done < <(dpkg-query --show --showformat \
         '${Package} ${Architecture} ${Version} ${Source}\n' '*linux*' |
         awk '$4 == "linux-meta" {print $1, $2, $3}')

if [ -n "$to_install" ]; then
    apt-get install $to_install
fi

if [[ $(uname -r) =~ 5\.11 ]]; then
    echo
    echo "*** NOTE NOTE NOTE ***"
    echo
    echo "You need to reboot, select the 5.10 kernel during boot, and"
    echo "rerun this script."
    echo
    echo "Before rebooting, make sure GRUB_TIMEOUT is set to a non-zero value"
    echo "and GRUB_TIMEOUT_STYLE is set to 'menu' in /etc/default/grub, and if"
    echo "you have to change either of them, run 'sudo update-grub' before"
    echo "rebooting. Otherwise, you won't be able to easily select the 5.10"
    echo "kernel when you reboot."
    echo
    echo "*** NOTE NOTE NOTE ***"
    echo
    exit 1
fi

if [ -n "$to_hold" ]; then
    apt-mark hold $to_hold
fi

# Uninstalling the 5.11 kernel

to_remove="$(dpkg-query --show --showformat \
         '${Package} ${Architecture} ${Version} ${Source} ${Status}\n' \
         '*linux*' | grep -v deinstall |
         awk '$4 == "linux" && $3 ~ /^5\.11/ {print $1 ":" $2}')"

if [ -n "$to_remove" ]; then
    apt-get remove $to_remove
fi

rm -rf $pd