Added jepler's kernel pinning script

rpi-pin-kernel-firmware.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+# rpi-pin-kernel-firmware: Pin a specific version of the rpi kernel and firmware
+
+set -e
+
+if [ $# -ne 1 ]; then
+    echo "Usage: $0 kernel-version"
+    echo
+    echo "e.g., $0 1.20201126-1"
+    exit 1
+fi
+
+if ! dpkg -l raspberrypi-kernel:armhf > /dev/null 2>&1; then
+    echo "This command is designed to run only on Raspbian with the armhf kernel"
+    echo 99
+fi
+
+
+if [ `id -u` -ne 0 ]; then
+    echo "If necessary, enter your password to run this script as root"
+    exec sudo sh "$0" "$1"
+fi
+
+version=$1
+base=http://archive.raspberrypi.org/debian/pool/main/r/raspberrypi-firmware/
+packagelist="libraspberrypi0 libraspberrypi-bin libraspberrypi-dev libraspberrypi-doc raspberrypi-bootloader raspberrypi-kernel raspberrypi-kernel-headers"
+
+set --
+for package in $packagelist; do
+    filename="${package}_${version}_armhf.deb"
+    set -- "$@" "$filename"
+    wget --continue -O "$filename" "$base/$filename"
+done
+
+dpkg -i "$@"
+
+for package in $packagelist; do
+    /bin/printf "Package: $package\nPin: version 1.20201126-1\nPin-Priority:999\n\n"
+done > /etc/apt/preferences.d/99-adafruit-pin-kernel