add non-free firmware into initrd.gz

inject_nonfree_firmware.sh

#!/bin/bash
set -e

# trap keyboard interrupt (control-c)
trap control_c INT

# Must be run as root
# requires: 
#   - wget
#   - pax

# shows how initrd.gz finds firmware, could potentially download all firmware debs and put them in /firmware.
#root@tftp:/var/lib/tftpboot/kernel/debian/wheezy/amd64/non-free/tmp# grep -ri "*.udeb" *
#bin/mountmedia: for filename in $dir/*.deb $dir/*.udeb $dir/*.ude \
#bin/mountmedia: $dir/firmware/*.deb $dir/firmware/*.udeb $dir/firmware/*.ude; do
#bin/check-missing-firmware: check_for_firmware /firmware/*.deb /firmware/*.udeb

# kernel.org git repo of firmware: http://git.kernel.org/cgit/linux/kernel/git/firmware/linux-firmware.git/tree/

INITRD="$1"
WORKING_DIR=/tmp/initrd
CURRENT_DIR="$(pwd -P)"

mkdir -p $WORKING_DIR

cleanup() {
  rm -rf $WORKING_DIR/*
  return $?
}

control_c() {
  # run if user hits control-c
  echo "Caught interupt. Cleaning up..."
  cleanup
  exit $?
}

main(){
  echo "Copying kernel and ram disk to non-free directory..."
  cp $INITRD $WORKING_DIR

  mkdir -p $WORKING_DIR/firmware
  cd $WORKING_DIR

  echo "Downloading firmware.tar.gz..."
  wget -cq http://cdimage.debian.org/cdimage/unofficial/non-free/firmware/unstable/current/firmware.tar.gz

  echo "Extracting firmware..."
  tar -C firmware -zxf firmware.tar.gz

  echo "Combining all debs in firmware.tar.gz into one gzip file..."
  pax -x sv4cpio -s'%firmware%/firmware%' -w firmware | gzip -c >firmware.cpio.gz

  # cd to the directory where you have your initrd
  cd "$OUTPUT_DIR"
  [ -f $INITRD/initrd.gz.orig ] || cp -p $INITRD $OUTPUT_DIR/initrd.gz.orig
  echo "Creating new ram disk with non-free firmware..."
  cat $OUTPUT_DIR/initrd.gz.orig $WORKING_DIR/firmware.cpio.gz > $OUTPUT_DIR/initrd.gz
}

usage(){
  echo "Usage: $0 </path/to/initrd.gz>"
  echo "  Copies your original initrd and injects nonfree drivers"
  echo "  into the RAM disk you specify."
}

if [ -z "$INITRD" ]; then
  usage
  exit
else
  OUTPUT_DIR="$PWD/$(dirname $INITRD)"
  cleanup
  main
  cleanup
fi

This entire script can now be done like this:

wget -O initrd_orig.gz http://mirror.cs.uchicago.edu/debian/dists/jessie/main/installer-amd64/current/images/netboot/debian-installer/amd64/initrd.gz
wget http://cdimage.debian.org/cdimage/unofficial/non-free/firmware/unstable/current/firmware.cpio.gz
cat firmware.cpio.gz initrd_orig.gz > initrd.gz